As I'm sure you've experienced, when shooting with the ATN Thor & HD Series Thermal Scopes, the standard factory mount is too low, which makes for a "contorted" sight picture.
This block raises the scope @ .700, so a better sight picture is possible. ADDITIONALLY... It allows for the retention of factory and most aftermarket folding sights, which would otherwise need to be removed before the scope is attached.
Inexpensive and easy to install.