5/6/20 - This is a rare Walther PPK 4mm conversion kit. This kit allows for a PPK to fire 4mm rounds, which are included in the kit (see photos). These are slightly smaller than .22 caliber rounds and intended for indoor firing range use. We believe this is an early commercial item made in the 1930s. Kit comes complete and the original box is in excellent condition. Excellent condition throughout, and the bore is about 9/10 with only some very minor residue, but this would likely clean to mint condition.