TMP UMP Style Semi Auto Receiver. Injection molded, glass filled polymer molded in black. Perfect for a "Parts Kit Build". These can be built out in any of the standard calibers: 9mm through .45. Check with HK Parts for Parts Kit Listings. We offer braces, stocks and barrels. We can also build out your parts kit to semi-auto and assemble it for $125 plus shipping if you send to us.