Features: 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. Specifications: Color: Black Materials: Aluminum, PC, ABS Compatibility: For all EF and EF-S Canon lenses Macro tube size: 6.2 * 8cm / 2.4 * 3.1in (D * H) Auto Distance Image Field Distance Exposure Extension Reading of Magnification Coverage From Lens Factor Tube Master Ratio (cm) Front to Lens Subject (cm) 13mm Inf. 0.24 10 * 15 21 1.5 0.5m 0.35 6.9 * 10.3 16 1.8 21mm Inf. 0.40 6 * 9 13 2.0 0.5m 0.51 4.7 * 7.0 14 2.3 31mm Inf. 0.72 3.3 * 5.0 7.7 3.0 0.5m 0.83 2.9 * 4.4 7.0 3.4 13+21mm Inf. 0.64 3.8 * 5.6 8.5 2.7 0.5m 0.75 3.2 * 4.8 7.5 3.1 13+31mm Inf. 0.96 2.5 * 3.7 6.0 3.9 0.5m 1.07 2.3 * 3.4 5.5 4.3 21+31mm Inf. 1.12 2.2 * 3.3 5.3 4.5 0.5m 1.23 2 * 3 4.9 5.0 13+21+31mm Inf. 1.34 1.8 * 2.7 4.5 5.6 0.5m 1.47 1.6 * 2.4 4.2 6.1 Package List: 1 * Macro Extension Tube Set 1、Support accurate TTL & Autofocus. 2、Built-in electric pins. 3、Upgraded circuitry to work better with digital SLRs cameras and SLR lenses. 4、Combined of 3 tubes with different length of: 13mm, 21mm, 31mm. 5、Superior lock pin which can tighten the tube joint.