Improved Double Glazed Locks Double glazed locks can be applied to heavy doors or windows for added security. And it will be more solid, solid and sturdy, exquisite workmanship, aluminum alloy frame and stainless steel screws which can be reused for 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 track no longer than 1.6cm / 0.63 inch (not applicable to middle track) window, please check your window track before purchasing)Easy to install - it is not no need to install any additional tools, it has a hex key in each window lock, held by a key control on the track. Designed for horizontal/vertical windows and sliding glass doors; Not for plastic window frames