ZWO 2-inch Filter Drawer with 21mm ring design is independently developed by ZWO, which includes M42 * 0.75 male thread (camera side) and M48 * 0.75 female thread (filter end), M48 * 0.75 female  thread (telescope side) as well.
The double strong magnets create stronger adsorption, easier installation and pulling out.
There is a lock screw on the side of it. The locking function is helpful on adjusting the tension to eliminate the gap, which is a double insurance for users.
 
With the ability of double strong magnetic adsorption, it is more convenient and much easier to install or pull out the filter.
 
The filter drawer also comes with the M48-M42 adapter. You can use it with your camera or your telescope.
 
 
Mechanical Drawing
 
66mm(height)*66mm(length)*21mm(thickness)
M42 * 0.75 male(external) thread (camera side)
M48 * 0.75 female(internal) thread (filter end)
M48 * 0.75 female(internal) thread (telescope side)
Suitable for 2-inch astronomical filters