MEASURE YOUR WINDOWS TRACK: The window lock is apply for sliding windows, sliding doors and vertical windows.please measure your window track size. window locks is equipped with a vertical key, which can be applied to the middle track of the window. UPGRADE PROTECTION DESIGN: Upgrade protection design,our each window lock has two fixing holes,secure it on the window track,which greatly enhance the holding power of the lock,use double hole locks on heavy windows/doors for added security. window locks are also equipped with protection pads to prevent scratches or damage to your window and improve stability. WIDE USAGE: It ensures your family members safety,can control the window partially open or closed,effectively reduce the risk of children and pets falling from high windows,by locking your windows, it can also protect your property against damage during heavy rains and hurricanes.also, it prevent burglars and thieves.This sliding window lock for home,bedroom, kindergarten, office,etc. EASY TO INSTALL: No additional installation tools or drilling required,3-step quick installation.step1,place the lock to a suitable position.Step2,Insert gasket protect window track from scratches.Step3,tighten the screws,done!you can easily fix the window lock at any part with the vertical key or hex keys,easy to reuse and re-install. PACKAGE INCLUDES: 4 Sets of window locks for sliding windows,including 4 PCS sliding window locks,4 PCS hex keys,4 PCS gaskets,1 PCS vertical key.