Aputure Macro Extension Tube Set is the perfect macro solution for your Canon lenses. There are 3 tubes of 12mm, 20mm and 36mm, which can be used individually or in combinations for 7 different possibilities. Main features include solid copper construction, accurate TTL metering & AE, built-in gilded electric pins , aluminum alloy sealing inside, sturdy build, and compatibility with a wide range of lenses, from wide angle to telephoto.

Specification:

• Model: AC-MC 
• Name: AC-MC Canon Macro Extension Tube
• Net Wight: 239.00g 
• Type: Canon Macro Extension Tube for Canon Camera EF & EF-S Lens 13mm 21mm 31mm
• Material: Metal
• Function: 13mm,21mm,31mm which can be used individually or in combinations for 7 different possibilities.
• Standard Configuration: Fit for All EF & EF-S Canon Lens

Compared to other cheap Macro Extension Tube on the market , the Aputure AC-MC Macro Extension Tube have some advantages: 

• The 3 tubes of 12mm, 20mm and 36mm, which can be used individually or in combinations for 7 different possibilities, can directly connect Canon camera EF & EF-S Lens or Canon Camera itself. It can realize the adjustment range of focusing distance from 4.2cm to 21 cm & Magnification from 0.24 to 1.47 
• It keep itself autofocus function & also realize mechanical focus 
• It keeps automatic metering function, realize third gear exposure complementary & predictability of Shooting exposure value