INSTALL each lock is equipped with a key, no extra tools needed, you just need spin the key slowly through the hole and hold on the track by key control. Please check your window track before buying. MATERIAL made of aluminum alloy, durable and rust-proof, can serve you for long time using UTILITY the window locks can be applied to keep windows partially open or closed, enhancing air circulation, preventing burglars from entering or keep your kids safety; Fits for most vertical or horizontal sliding windows and doors SIZE the lock size is approx. 2.4 x 2 x 1.4 cm/ 0.94 x 0.79 x 0.55 inch (LWH), key length is approx. 2.7 cm/ 1 inch, apply to track heights more than 5 mm/ 0.2 inch and track thickness no greater than 6 mm/ 0.23 inch, please check the size before ordering. PACK include 12 pack window lock.