Spiritus Systems
Micro Fight Chassis Mk4
$75.95
You want a modular placard with unmatched customization options and third-party ecosystem support.
You want an all-in-one solution without buying multiple accessories to complete your setup.
Quick Verdict
The Micro Fight Mk4 is the modular placard that started a revolution. At $75.95 for the chassis alone, it's not the cheapest option - but the ability to completely customize your loadout with inserts, flaps, and the largest third-party accessory ecosystem in the industry makes it the most versatile choice for users who want a system they can reconfigure as needs change. If you value flexibility over convenience, this is the benchmark everything else is compared to.
Overview
The Spiritus Systems Micro Fight Chassis Mk4 is a two-pocket placard designed as the central hub of a modular chest rig system. Founded in 2013 by 82nd Airborne veterans, Spiritus built the Micro Fight around a simple concept: use velcro as the primary attachment method to enable unlimited configuration options. The Mk4 iterates on the proven Mk3 design with improved rear velcro coverage and integrated tourniquet grommets for the Universal Retention Kit.
Where competitors like the D3CRM come as complete packages, the Micro Fight takes the opposite approach - the chassis itself holds nothing without adding inserts. This "buy what you need" philosophy appeals to users who want total control over their loadout, though it means higher total cost for a complete setup. The tradeoff is genuine modularity: swap between 5.56, 7.62, SMG, or pistol magazine configurations in seconds, or strip it down to a minimalist placard for plate carrier use.
Specifications
Specs verified against manufacturer website
| Dimensions | 9" (L) x 5" (H) x 2.5" (W) |
| Material | 500D Cordura |
| Rear Hook Field | 5" x 9" (full coverage) |
| Front Loop Field | 8" x 4" (for patches/ID) |
| Pocket Configuration | Two tiered pockets with soft loop interiors |
| Drainage Grommets | 3 (1 rear pocket, 2 front pocket) |
| TQ Grommets | 2 (compatible with Universal Retention Kit) |
| Buckles | 2 fixed (top), 2 removable (sides) |
| Colors | MultiCam, M81 Woodland, Ranger Green, Coyote, Black, Wolf Grey, MultiCam Black, MultiCam Tropic, MultiCam Arid |
| Made In | USA |
| MSRP | $75.95 |
Pros
- ✓Unmatched modularity - swap magazine configurations in seconds
- ✓Largest third-party accessory ecosystem (AXL, Microbat, Wild Bill, etc.)
- ✓Full rear velcro coverage for solid plate carrier integration
- ✓Works as standalone chest rig OR placard on carrier
- ✓Two-pocket design separates rifle mags from admin/pistol
- ✓Integrated TQ grommets for Universal Retention Kit
- ✓Elastic inserts are quiet during mag removal/insertion
Cons
- ✗Chassis alone holds nothing - must buy inserts separately
- ✗Complete setup costs $130-175 vs $140 all-in-one competitors
- ✗Fat Strap has no ride height adjustment
- ✗Popular colors frequently out of stock
- ✗No built-in GP pouch (front pocket only works with flaps)
Known Issues
⚠ Elastic inserts loosen with use.
By design, elastic will loosen over time but still provides adequate retention. Store with magazines inserted to maintain tension. Inserts are replaceable.
⚠ Fat Strap ride height not adjustable.
Taller/thinner users report the chassis hangs low when H-harness is positioned correctly between shoulders. Consider third-party straps from Unobtanium or similar if ride height is critical.
⚠ Gen 3 PMAGs tight fit during insert installation.
User tip: Cover velcro with cardboard pieces when sliding inserts into pocket to prevent snagging. Once installed, operation is smooth.
What You'll Need to Run It
Required
- Magazine Insert (Triple 5.56 or Double 7.62)$24.95
For Chest Rig Use (No Plate Carrier)
- Fat Strap Mk4 (H-harness)$49.95
- Back Strap$14.95
Optional but Recommended
- Half Flap Mk2 (mag retention, minimal)$19.95
- Full Flap Mk2 (mag retention + admin)$33.95
- SACK Pouch (dangler for IFAK/GP)$49.95
- Universal Retention Kit (TQ mount)$9.95
- Expander Wings (side pouches)$44.95
Typical Complete Setup: Chassis ($75.95) + Triple 5.56 Insert ($24.95) + Full Flap ($33.95) + Fat Strap ($49.95) + Back Strap ($14.95) = $199.75
Compatibility Chart
Compatibility data last verified: February 2026
Plate Carrier Compatibility
| Plate Carrier | Status | Notes |
|---|---|---|
| Spiritus LV-119 | ✓ Official | Native integration, designed for each other |
| Crye Precision JPC 2.0 | ✓ Verified | Standard velcro placard interface |
| Ferro Concepts Slickster | ✓ Verified | Works with standard front flap |
| Ferro Concepts FCPC v5 | ✓ Verified | Standard velcro placard interface |
| Defense Mechanisms MEPC | ✓ Verified | Standard velcro placard interface |
| T.REX Arms AC1 | ✓ Verified | Standard velcro placard interface |
| Velocity Systems Scarab LT | ~ Likely | Standard velcro interface dimensions |
| Shaw Concepts ARC v2 | ~ Likely | Standard placard-compatible front |
Spiritus Systems Accessories
| Accessory | Status | Price |
|---|---|---|
| Triple 5.56 Rifle Insert | ✓ Official | $24.95 |
| Double 7.62 Rifle Insert | ✓ Official | $24.95 |
| Single Rifle Insert | ✓ Official | $19.95 |
| Quad SMG Insert | ✓ Official | $24.95 |
| Double Pistol Insert | ✓ Official | $19.95 |
| Single Pistol Insert | ✓ Official | $14.95 |
| Full Flap Mk2 | ✓ Official | $33.95 |
| Half Flap Mk2 | ✓ Official | $19.95 |
| Fat Strap Mk4 | ✓ Official | $49.95 |
| Back Strap | ✓ Official | $14.95 |
| SACK Pouch Mk3 | ✓ Official | $49.95 |
| Expander Wings Mk2 | ✓ Official | $44.95 |
| Thing 2 Chassis | ✓ Official | $54.95 |
Third-Party Accessories
| Accessory | Status | Notes |
|---|---|---|
| AXL Hi-Top Zipper Insert | ✓ Verified | Popular GP pouch alternative to flaps |
| AXL Half Zipper Insert | ✓ Verified | Slimmer zippered admin option |
| AXL SLAP (for danglers) | ✓ Verified | Mounts Crye GP pouches as danglers |
| Ferro Mini Dangler | ✓ Verified | Excellent form factor match |
| Beez Combat Sidewings | ✓ Verified | Alternative to Spiritus Expander Wings |
| GMR Kydex Inserts | ✓ Verified | Rigid alternative to elastic inserts |
✓ Official = Manufacturer confirmed |✓ Verified = Community confirmed (3+ sources) |~ Likely = Should work based on specs
Best For
Users who want maximum configurability and plan to adapt their loadout over time. If you run multiple weapon platforms, want to swap between 5.56/7.62/SMG configurations, or value the extensive third-party ecosystem from AXL, Beez Combat, and others, the Micro Fight is the most flexible platform available. Also ideal for users who already own a Spiritus LV-119 or plan to.
Who Should NOT Buy This
- ✗Want all-in-one solution - get the D3CRM Micro instead
- ✗Need built-in GP pouch - consider D3CRM or Micro Fight MkV + CCS Pouch
- ✗Budget under $100 for complete setup - total cost runs $130-200
- ✗Prefer MOLLE attachment - the Mk4 is velcro-based
Variants & Options
Available Colors
Note: Popular colors (MultiCam, Ranger Green) frequently sell out. Check multiple retailers or sign up for restock alerts.
Where to Buy
Prices last verified: February 2026
Want to know when this drops below $75? Track this placard →
Alternatives to Consider
If you want an all-in-one placard with built-in GP pouch and included inserts. Less modular but ready to run out of the box.
If you want MOLLE on the front and a slimmer single-cell design. Pairs with CCS Pouch for GP storage. Newer design but less ecosystem support.
If you want Kydex retention included. Fixed configuration (3x 5.56) but excellent retention without aftermarket inserts.
FAQ
Can I use the Mk4 without buying any accessories?
No. The chassis alone has empty pockets - you need at least one magazine insert ($24.95) to hold anything. For chest rig use without a plate carrier, you also need the Fat Strap and Back Strap.
What's the difference between Mk4 and MkV?
The Mk4 has two tiered pockets (front and rear), a large front loop panel for patches, and relies on inserts + flaps for organization. The MkV is a single-cell design with MOLLE on the front, designed to pair with the CCS Pouch for GP storage. Both have the same footprint and work with the same straps/carriers.
Will it fit on my plate carrier?
If your carrier has a front velcro placard interface (most modern carriers do), yes. The 5" x 9" hook field on the back provides excellent attachment. Remove the side buckles when using as a placard.
How many magazines can it hold?
With inserts in both pockets: 6x 5.56 magazines OR 4x 7.62 magazines. You can also mix configurations (rifle in rear, pistol in front, etc.).
Is the D3CRM better than the Micro Fight?
Different tools for different needs. The D3CRM is better if you want a ready-to-run all-in-one solution with built-in GP pouch. The Micro Fight is better if you want maximum configurability, plan to swap configurations, or want access to the extensive third-party accessory ecosystem.
Affiliate Disclosure: TacVault earns a commission from purchases made through links on this page. This doesn't affect our recommendations - we recommend what we'd actually buy. Inclusion does not imply endorsement or affiliation with the manufacturer.
Specs verified against manufacturer website on February 2026. Compatibility data compiled from manufacturer documentation, community testing, and verified user reports.