Colt 22-45 Service Model Conversion Unit. This is the 1st of the Colt built conversions with only 2670 built., some were unnumbered. This was a cheaper way to target practice, than to buy an Ace-22. This is is lightly used with about 95% blue and an excellent bore, in the original numbered cardboard box with the manual. The lid of the box shows some professional repair. All parts are included.