Glock Factory OEM 10-coil Spring fits G17 – 17round 9mm magazines as well as G20 15round .10mm; G21 .45ACP; G22 15 round .40 caliber; and the G34 and G35 magazines.
Glock Factory 10 Coil Spring Fits the Following Models:
G17, G18, G34 17 round magazines including Pre-Ban, LE Marked, & current unmarked magazines
G20 15 round magazines
G21 13 round Pre-Ban & older LE marked mags with follower 3955
G21 10 round magazines
G22, G35 Pre Ban and older LE marked mags (Will not work with Tac Light)