Handcuffs Double Locking NickelSingle or Double Lock Handcuffs. Handcuffs with the double lock have a push button on the side that prevent the handcuffs from being opened or over tightened. Button is pushed with the tip of the key to engage the lock. To disengage the lock insert the key into the lock and rotate the key counter clockwise 90 degrees (then rotate clock wise 180 degrees to open the cuffs). All handcuffs come with 2 keys.