Is 1/4” deep ok for 1/2” plywood installation? I didn’t see any 3/8 depth Is the offset 1 1/6” on top and bottom of hinge = 2 1/4” combined? Are these hinges available with spring assisted version

Depending on your case and how you are using it, it should be okay to use a 1/4" / 7mm deep lid stay on a 1/2" / 12.7mm plywood. 

The offset is 2 1/8”/ 54mm combined.

This lid stay is not available with spring assist or at 3/8” / 9.53mm depth as present, but we will keep this in mind when introducing new ranges in the future.

- Penn Elcom.