15 Round Sig Sauer 228 & 229 22LR Conversion Magazine upgrade turns your 10 round magazine into a 15 round magazine.
Sig Sauer 229 22LR replacement magazine spring for 22 long rifle conversion kit magazines
Sig Sauer 229 22LR Last Round Hold Open Follower. This follower locks the slide back on an empty magazine. It does NOT utilize the slide lock on the gun but rather engages the bolt face on the slide.