max door thickness

Thanks for writing in. The handles of the 40-183 are typically used on a 1" thick security door. That said, I believe it could work on a 1-3/4" thick door by adjusting the length of the lever handle and locking it in place with the set screw. Let me know if that makes sense. If you're in doubt, show us pictures of the handle set you currently have so we can confirm that the 40-183 is indeed the right choice.