Here are the actual mechanical parts, including two guide pins that center the heat sink on this assembly. The lens tube is machined with three protruding bumps surrounding each end, undercut for elasticity, and will stay in place during adjustment for focus and azimuth. The tubes are aluminum with a nickel plating. The surface grooves are to secure the lens tube in place with injected glue -- also known as "VOFIMA", or "volume filling material", by those who will never use glue. 055