It works good, but needs small improvements.
I replaced the 4 screws that hold the white plastic,with stainless steel ones ( they won't corrode and look good with the case. I put small lengths of silicone rubber tubing on the tilt wire, where the wire touches the table to keep it from scatching the table and it won't slide off. I glued a 1/4" thick strip of plexiglass to the bottom of the white plastic to keep the slides from falling off the plastic when the unit is tilted.
I originally purchased it to register front and back artwork that I use for photoresist metal etching. Also great for sorting slides.
If you're looking for a small, portable and rugged transparency viewer, this is it. Tuck it under your arm, or put it into a computer bag to take it with you. The light is very even, eliminating the need to reposition slides when viewing them. There are two viewing positions (slightly angled and flat). I appreciate the flat position when sorting stacks of slides; the stacks don't topple over.