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 that can be re-used several times. Quantity and size - double sliding window locks with 4 cls approximate volume 6 x 2.54 x 2.4 cm / 2.36 x 0.95 x 0.95 inch (LWH), apply track heights greater than 1.2 cm / 0.47 inch, thickness of the 1.6cm / 0.63 inch (not applicable middle lane) window not top lane, please check your window track before purchasing). Easy to install - it is not necessary to install additional tools, it is equipped with a hexagonal key in each window lock, maintained by a key control on the track. Designed for horizontal / vertical windows and sliding 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 Anti-theft devices and thieves can prevent children from falling and protect the safety of their families while improving air circulation. Product Guarantee and Customer Service - We do not sell perfect pictures but of products We provide full refund or free re-shipment of new products for free if you are not satisfied with our products.