The file 'UpLULA Spacer For Sig P229 Magazine 3D Printer Model' is (stl) file type, size is 11.5KB.
This is just a remix of the UpLULA Spacer made by RockyMtnMark, to fit the p229, p224, and similar Sig mags, since the original double stack mag was too thick-walled for these mags to fit.
