SLR Rifleworks Glock 21 Compatible Magazine Extension +4

Manufactured by SLR Rifleworks


In Stock

NOTE: Limit 10 per household. Quantities exceeding 10 will not allow checkout.

We are fully staffed and processing orders. Standard orders are shipping in approximately 2 business day. FFL orders take approximately 14-16 business days if you can provide us an actively receiving FFL location.


In Stock


A few extra rounds can be the difference between a costly reload on the clock and crushing a stage. The SLR Rifleworks +4 magazine extension installs quickly and easily to your favorite Glock factory or ETS magazine for the Glock 21 handgun, bringing your capacity to an impressive 21-rounds per magazine. Machined from high strength 6061-T6 aluminum, these extensions also add additional mass to ensure your magazines reliably drop free during reloads.


  • For factory and ETS Glock 21 Magazines
  • Adds +4 capacity
  • Machined from 6061-T6 aluminum
  • Hardcoat anodized matte black
  • Increased mass for reliable drops
  • Requires extra power spring (sold separately)

SLR Rifleworks is a firearms manufacturer based in central Florida that specializes in bringing new, innovative parts to the AR-15 platform. SLR has even expanded into the AK-47 and Glock platforms with various components like stocks, muzzle devices, and magazine wells.


BrandSLR Rifleworks
MaterialAluminum - 6061-T6
PlatformGlock Magazines

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