The phot r 37mm centre pinch snap on front lens cap with holder has a squeeze spring and snap on mechanism theyre easy to put on and take off especially when using a lens hoods and they stay on as intended lens caps protect your lens from scratches fingerprints and dirt when the lens is not in use its always good to have a spare lens cap in your camera bag too this lens cap comes with a holder which you can attach to your camera when the lens is in use so you dont lose itlens cap is