Extend your Glock 21/41 from 13, to a full 17 rounds of firepower!
Built for USPSA's "Limited" Division, the finished magazine is 140mm long, as measured down the back (versus about 120mm stock). Also works (as a +5!) on the 10mm G20.
Ships with a custom-made Wolff spring.
HISTORY: Glock's early .45 ACP mags used a 9mm-width spring -- with mixed results. The newest design uses a full-width spring, eliminating the problems of the earlier style. When the wide springs became available, we re-designed our old G21+4 to take advantage of them -- and extended the length to fit the new USPSA gauge at the same time. The result is a +4+ situation that's simpler and more reliable than the old skinny-spring G21
NOTE: Our new springs don't fit the older skinny-spring followers very well. They will work, but you're better off getting new mags with the new chisel-nose followers.

review
quality is very good