The Strike Industries AR-10 Enhanced Lower Receiver Parts Less Trigger, Hammer and Disconnector includes most of the necessary parts to build (or enhance/upgrade) a lower receiver minus the trigger group, pistol grip and trigger guard for those lowers that dont have one built-in. This kit includes all the basics that you will need to build out a new lower and a perfect pairing with the many various style SI AR Grips available. Reuse an existing AR trigger group or the freedom to pick your own AR trigger you rather have and not get stuck with a plane jane Mil-Spec trigger will just collect dust in a drawer somewhere. However, the hammer and trigger springs along with pins are included in the bag. The Strike Industries AR-10 Enhanced Lower Receiver Parts Trigger, Hammer and Disconnector includes SI signature enhanced lower parts like the bolt catch, magazine release, pivot/takedown pins and HEX Selector Switch that offers both a 60 or 90-degree angles 3 in1 combo, no other lower parts kit (LPK) on the market gives you the most bang for your buck. Specifications for Strike Industries AR-10 Enhanced Lower Receiver Parts Less Trigger/Hammer and Disconnector: Manufacturer: Strike Industries Color: Black Fabric/Material: 6061-T6 Aluminum Gun Make: AR Platform Gun Model: AR-10 Gun Type: Rifle Weight: 3.1 oz Features of Strike Industries AR-10 Enhanced Lower Receiver Parts Less Trigger/Hammer and Disconnector Includes SI's signature Enhanced Lower Parts: Strike AR-10 Enhanced Bolt Catch (SI-AR-EBC) Strike Magazine Catch - Black (SI-AR-SMC) SI Extended Pivot / Takedown Pins (SI-AR10-EPTP) (coming soon) HEX Selector Switch 60/90 degree 3 in 1 (SI-AR-HS-60/90-3in1) Freedom to pick your own AR trigger group (AR hammer and trigger springs + pins are included) Included SI enhanced components at a cost-effective LPK price Perfect pairing with one of the various SI AR Grips available Package Contents: Strike Industries AR-10 Enhanced Lower Receiver Parts Less Trigger/Hammer and Disconnector SI ENHANCED PARTS: 11pcs Strike AR-10 Enhanced Bolt Catch - features improved grip surfaces and angles Strike Magazine Catch Strike Magazine Catch button - features improved grip surface SI Extended Pivot Pin - longer of the two large pins SI Extended Takedown Pin - smaller of the two large pins HEX Selector Switch - x2 included HEX Selector Switch end cap HEX Selector Switch 60/90-Degree shaft with screws - x1 shaft and x2 screws SPRINGS: 9pcs Bolt Catch Spring - easily confused with the disconnector spring disconnector spring is tapered though Magazine Catch Spring - this is the largest coil spring in the kit Pivot Pin Detent Spring - same as the takedown detent spring so there are two in a kit Takedown Pin Detent Spring - same as the pivot detent spring so there are two in a kit Selector Spring - similar to the takedown and pivot detent springs but larger diameter there will only be one of these Buffer Retainer Spring - second largest coil type spring in the kit Hammer Spring - largest of all the springs Trigger Spring - the smaller of the two largest springs Disconnector Spring - slightly larger than bolt-catch spring identifiable because one end is a little bit wide than the other PINS/DETENTS/OTHERS: 8pcs Bolt Catch Plunger - mushroom shaped pin Bolt Catch Roll Pin - smaller of the two roll pins Pivot Pin Detent - same as takedown detent both sides usually rounded or semi-conical Takedown Pin Detent - same as pivot detent both sides usually rounded Selector Detent - one end is flat the other pointed/semi-conical Buffer Retainer - large hollow barrel with small pin protruding from the top Hammer Pin - solid pin with machined grooves can be inserted from either side Trigger Pin - same as hammer pin can be inserted from either side