This Ruger manufactured third variation 9 round magazine assembly is for the later "A100" style Mark I semi-auto pistol with the magazine button flare on the left side of the frame. This magazine is in very good condition with honest wear and possibly a few specks of surface rust. (file photo)

Note: This variation magazine can have its thumb button easily moved from the left side to the right side for earlier style pre-A100 Mark I pistols if needed.

Note: Ruger Mark I semi-auto pistols with the following serial numbers have been observed with this part:

12-11122 & 12-72207

16-58723

17-33228