Question: what is the difference between a grade 1 and a grade 2 lock?
Answer: Grade 1 requires a key in knob must hold up to 300 lb-in and a lever lock must withstand 450 lb-in. Grade 2 requires a key in knob, must hold up to 150 lb-in and a lever must hold up to 225 lb-in. Grade 3 requires a key-in-knob to withstand at least 120 lb-in and a lever lock must withstand at least 180 lb-in.