This Lockmaster is one of the most popular and features anti lift pins below each of the hooks to offer enhanced security. Please note that the double spindle version is unsprung and should only be used with sprung handles. 
Operation: Lift lever or double spindle nightlatch.
Latch reversal: Undo the screw or screws (depending on the model) in the latch to remove. Reverse, reinsert and replace screw(s).