Lantac M-SPEC Upper Parts Kit (UPK) for AR15 style rifles. – Manufactured to the highest quality standards using correct materials heat treatments and finishes to comply with up to date military specifications. – Kit includes the following: – Bolt Catch Plunger – Bolt Catch Plunger Spring – Bolt Catch Roll Pin – Bolt Catch Set Screw (6-32 compatible with Lantac Aero and other lowers). 1/16th Allen Key Head – Buffer Retainer x2 – Buffer Retainer Spring x2 – Takedown Pin Detent x2 – Takedown Detent Spring x2 – Pivot Pin Detent x2 – Pivot Pin Detent Spring x2 – Trigger Pin x2 – Safety Selector Detent x2 – Safety Selector Detent Spring x2 – Lifetime Warranty. – Made in the USA.