Apply to windows and doors: make sure the track heights more than 1.5 cm/ 0.6 inches, track thickness no more than 1.6 cm/ 0.63 inches, not applicable to the middle track of the window, please check your window track before buying^ Convenient to install: each lock is equipped with hex key, spin the key slowly through the hole, just holding on the track by key control, no additional installation tools^ Quality material: made of aluminum alloy, which is sturdy and strong, and theres a yellow plastic cover outside the key handle, can serve you a long time^ Necessary items: open the screen window when the weather is hot in summer, which can improve air circulation, you can use the window locks to fix the screen window, it can prevent children from falling and prevent the thieves^ What you get: 8 x sliding window locks with key; Note: multiple locks can be applied to heavy window or door together to increase safety ^