The extended length focusing ring is precision-machined from aircraft grade aluminum and is designed to fit standard 9mm diameter lens assemblies. It is nearly 1/2" long with a knurled outer surface and allows easier focusing without burning your fingers. The outside diameter is sized to fit commonly-used protective lens caps. A taper is machined into the output end of the ring which gives it a "rocket nozzle" appearance. Black anodizing matches our black anodized heat sink.