Built-in electric pins. Perfect for macro shooting. Support accurate TTL & Autofocus. Compatible with all EF and EF-S Canon lenses. * Diaphragm control of the lens can set automatically. All the 3 parts can be separated as one adapter tube to use. Each adapter tube has 8 electronic contacts. * Upgraded circuitry to work better with digital SLRs cameras and SLR lenses. With lock pin. High quality and compact. Made of brass and Aluminum (not plastic). * If the tubes are correctly attached, TTL metering and Autofocus performance will function as usual. When using Non-TTL camera, you must adjust aperture and shutter before shooing to ensure correct exposure. * This adapter is used by attaching between camera body and lens of the 35mm single-lens reflex camera. It comes as a set of 3 tubes of different lengths which singly or in combination on makes it usable in 7 different lengths.