Support accurate TTL & Autofocus. Built-in electric pins.Compatible with all EF and EF-S Canon lenses. Combined of 3 tubes with different length of: 13mm, 21mm, 31mm.Made of high-quality Aluminum material that is stronger.Upgraded circuitry to work better with digital SLRs cameras and SLR lenses. Superior lock pin which can tighten the tube joint.Perfect for macro shooting. High quality and compact.