The 1.25 inch Variable Universal Camera Adapters allow attachment of a camera body to reflector and refractor telescopes for either prime-focus or telescope eyepiece-projection photography. T Interface: 1.25 inches Tail Thread: M42x0.75 thread Variable Length: 38mm Usage: for Professional Astronomy Telescopes Camera Photography Tips:For eyepiece projection photography, the maximum outer diameter of the eyepiece is 37mm. Colour:Black Material:Aluminum Alloy Package Contents: 1 x 1.25 Inch Telescopic Extension Tube Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.