Ultra slim motorized filter wheel - only 0.7" thick! Holds 8 x 31mm unmounted filters up to 4mm thick using our proprietary zero-stress retainers. USB controlled and powered (no additional power supply required). No motors protruding from the filter wheel to get in the way. Measuring only 7.6" x 8" x 0.7", this is one of the smallest, thinnest motorized filter wheels on the market. Only adds 19mm of back focus to the optical path when used with our adapters. Perfect solution for ZWO ASI, QHY, ATIK, Moravian, SBIG cameras, and more.