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80% Arms sells AR-15 and .308 80% Lower Receivers, 80% Lower Jigs and other accessories which allow you to legally build a firearm at home in most states.
We utilize state of the art 5-axis CNC machines to mill all our .308 and AR-15 80 percent lower receivers to incredibly precise tolerances using premium billet aluminum.
We also offer our patented AR-15 and .308 Easy Jigs® which is the first 80% lower jig that makes it ridiculously easy for a non-machinist to finish their 80% lower in under 1 hour with no drill press required.
Products manufactured by 80% Arms carry a lifetime warranty against manufacturing defects. We will promptly replace or repair any product that we determine to be defective.

S365 Modular Grip

Additional Configurations
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Smith Defense, an American design and manufacturing company crafting premium firearm parts and accessories, proudly introduces its inaugural product: the S365 - a billet aluminum modular grip module for the SIG Sauer P365.  

The S365 includes interchangeable dust covers featuring a 1913 Picatinny accessory rail and are available in both standard 365 and 365L “long” configurations. 

Benefiting from its full billet metal construction, the base S365 adds approximately 4 ounces to your FCU, to help tame your pocket pistol. Smith Defense’s S365 has the ability to accept custom grip panels, enabling you to tailor its ergonomics for the most secure and personalized grip. 

Designed for a drop-in fit, the S365 seamlessly integrates with your Sig P365 FCU, guaranteeing proper function right out of the box. 

Not a firearm. No milling required 

Patent Pending

To view instructions head over to

Get your S365 grip with confidence, backed by our 30-day full money back guarantee, this means no risk to you. We will send you a prepaid return shipping label if you are unhappy with your S365!


  • Configurations: Easily switch across a P365, P365X, P365XL, and the unique P365L setup. 
  • Compatibility: Compatible with your existing lights and lasers as well as your favorite slides and barrels 
  • Durability: Milled from a solid block of aluminum using CNC machining, the S365 provides outstanding strength and rigidity
  • Ergonomics: Refined design and textures provide a more secure and comfortable grip, boosting accuracy and control.
  • Ease: Engineered for a drop-in fit with Sig P365 FCU’s, ensuring reliable performance right out the box  




  • 1 S365 Grip
  • 1 standard dust cover
  • 1 set of grip panels 
  • Hardware required (screws+wrench)  

Additional Information:

  • Mag release sold separately or you can use your existing mag release.

  • Accepts all P365 FCU units. (Manual safety units require removal of safety.)

  • The 1913 Picatinny Rail is slightly larger than Sig's proprietary rail and fits all P365 light-bearing holsters