2A manufactures some of the lightest AR15 parts for your custom rifle build. They produce lightweight gas blocks in both titanium and steel. Most notably, their upper and lower lightweight receiver sets are the lightest in the industry. You can choose from their Balios Lite Gen 1 and Gen 2 receiver sets and handguards.
Their Aethon line of rails and receivers were the first fully billet lightweight receiver sets on the market. If you're looking to build an AR10, AR308 or any other large frame rifle, then the XANTHOS Lite feels like a small frame 308 but still shares compatibility with other large frame parts.