Aputure macro extension tube set is the perfect macro solution for your Nikon AI 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 & AEbuilt-in gilded electric pins aluminum alloy sealing inside sturdy build and compatible with a wide range of lenses from wide angle to telephoto. Main Features 1. Copper macro extension tube collector edition; Incredible matte surface treatment; Built-in gilded electric pins; Supports accurate TTL metering & AE; Professional and compact outer design; Flexible combinations; Light and portable