These industrial-grade steel wrenches work in tight spots when ordinary allen keys won't. Each has one ball-end, permitting entry angles up to 25 degrees (the other end is standard).

This US-fit set of 11 wrenches includes the following sizes:

.050", 1/16", 5/64", 3/32", 7/64", 1/8", 9/64", 5/32", 3/16", 7/32", 1/4"

I use them in the workshop all the time – especially the hard-to-find .050” one, which fits US Fender bridge height screws.