Baader T2-17F enables the use of a a standard 2" astronomy filter in an SCTs light path. With the T2-17F, any filter can be permanently mounted as a means of dust sealing the OTA, or for convenient use with multiple eyepieces and accessories. The Badder T2-17F consists of two parts: T2-17A Visual Back and T2-17B 2" Filter Holder. These parts are not available separately. The eyepiece holder has a bronze clamping ring and two locking screws. Parts 17A and 17B connect to each other with M58 threads.