The all metal structure and anodized aluminum oxide process are durable and can be used for a long time.This extension tube can be used to obtain the correct image ratio or the exact spacing required for the reducer or field flattener.The extension tube has T2 internal thread and T2 external thread, which is used to solve the spacing problem in astronomical photography and eliminate a series of focusing problems.Type: Astronomical T2 threaded extension pipeExternal thread: M48 * 0.75mmInternal thread: M48 * 0.75mmProduct display of connecting or extending M48 * 0.75 pipe length productsVariable extension: 24-35mmPackaging content:Metal 24-35mm M48 variable extension tube