Are you having trouble focusing your eyepiece or camera? Then use this BRESSER 37.5 mm extension sleeve to increase the distance between the 2.0 inch Rack & Pinion focuser and the eyepiece or camera. The extension sleeve has an M54x0.75 mm internal and external thread and can therefore be screwed directly onto the HEXAFOC draw tube. Suitable for the EXPLORE SCIENTIFIC ED APO Essential series, among others.