The JMI Telescopes 2" to 1.25" or T-Thread Adapter allows 1.25" eyepieces to be used with diagonals, prisms, or focusers with a 2" inner diameter. You'll be able exchange between 2" and 1.25" eyepieces at will. Being a premium JMI product, it uses a brass clamping ring (instead of a simple set screw) to secure eyepieces without marring them.
This adapter is also threaded to accept a T-mount SLR camera adapter, facilitating imaging with your telescopes. Just affix your camera system's specific T-mount adapter and then add the two together to your SLR camera, which can then be inserted directly to the 2" focuser.