1.The ring recessed door knob is made of 304 Stainless Steel, premium quality zinc alloy and brass copper. Which can guarantee rust-free in a high humidity environment. 2.The door latch can be works for doors with thickness ranging from 1 1/6'' (29mm) to 1 3/4" (80mm). There are four blots, you can chose the size that you need according to the thinkness of the door. Suitable for passager door, furniture door, Kitchen door, Bedroom door, Closet door, Bathroom door, Passage door and so on. 3.There are four bolts come with the low profile door knob. you can cut the long bolt according to thickness of your door.. 4. Material: 304 Stainless Steel, copper, zinc alloy and plastic. Finished: Silver 5. If you have any not satisfied with your purchase, please contact us.we will help your issue.