Black Arredondo smooth magazine extension fits Pre Ban Hi-Capacity FML (Full Metal Lined) and NFML (Non Full Metal Lined) magazines. Virtually unbreakable and extremely secure. Easily installed or removed with supplied U tool. You are purchasing a complete kit which includes: Extra power spring, take down tool, extension sleeve and base pad.
+4 for Glock 9mm M/17, 17L and 34
+3 for Glock 40 S&W M/22, 24 and 35
+3 for Glock 357 Sig M/31
+2 for Glock 45 GAP M/37
*Designed to meet ISPC box rule.
Fits perfectly into IPSC Standard division box (if you dont have high sights), fits 20 rounds or 21 if you comprezz it really well (ex. using Maglula), but with 21 rnd is hard to lock into the gun.
Seems like there's mixed reviews online about exactly how many rnds of a particular caliber will fit easily with this extension. I added +3 rnds of .40 S&W to a factory Glock G22 15-rnd mag for a total of 18 rnds. But only barely, the last rnd is very difficult to load and it's almost impossible to insert on a closed slide. But even down-loading to 17+1 is still a good set up considering the extension adds less than 1" to length of the mag. Easy to install, longer/extra power spring appears to be a quality part. Had 0 feeding malfunctions at the range and slide always locked open after last rnd.