5" long Screws into 1.25 SCT adaptor. This is made by Celestron, the walls are .25" thick. The inside is spiril baffled for dark images. This is an eyepiece projection tube for high power photography. There are male T threads on the end. The eyepiece has to be slid down the tube after the tube is screwed on. Then the eyepiece set screw can be tightened.
Sell for $19.00 plus $4.95 Shipping CONUS ONLY. Thanks Phil