This Canon EOS Lens Adapter for 2" EFW Filter Wheel allows the use of full-frame Canon EOS lenses with ZWO 2" Electronic Filter Wheels and ASI cooled astronomy cameras. The adapter has an EOS bayonet on the lens side and an M54 x 0.75 thread on the EFW side. It is compatible with all ZWO Pro cooled cameras with APS-C or larger sensors. The adapter is not compatible with EF-S or mirrorless lenses.