" Upgraded double glass locks - Double glass locks can be applied to heavy doors or windows for more security. And it will be more solid, strong and sturdy, exquisite workmanship, aluminum alloy frame and screwsmade of stainless steel that can be reused many times Quantity and size - double sliding window locks with 4 keys; approximate volume 6 x 2.54 x 2.4cm / 2.36 x 0.95 x 0.95inch (LWH), apply to track heights above 1.2cm / 0.47inch, thickness of the way not greater than1.6 cm / 0.63 inch (not applicable to middle lane) window, please check your window track before purchasing) Easy to install - no additional tools required, it has a hex key in each window lock, held by a keyed control on the track. Designed for horizontal/vertical windows andsliding glass doors; Not for plastic window frames Wide use - can be easily applied to most environments; By keeping the windows partially open and closed, the burglars and thieves can prevent children from falling and protect the safety of their families.while improving air circulation "