Like the other reviewer, I find it hard to open onehanded without practice - The twistlock is designed funky, where the top part will clear the hook, yet the bottom will not clear the hinge without another 1mm or so of twist. Could easily fix it with a file, but rather not. At the widest point, across spine to hook, is 3" wide. Height is a little over 4" tall. About 1" of space on the inside at the bottom, and 2" inside across the top.
Reviewed by: George H from NW FL.