Upgraded Double Glass Locks - Enhanced Security : Our double glass locks are engineered for heavy doors and windows, providing superior security. Made with an aluminum alloy frame and stainless steel screws, these locks are solid, durable, and crafted with exquisite workmanship. - Quantity and Size : Each package includes double sliding window locks with 4 keys. The dimensions are approximately 6 x 2.54 x 2.4 cm / 2.36 x 0.95 x 0.95 inch (LWH). These locks are suitable for window tracks with heights greater than 1.2 cm / 0.47 inch and thicknesses not exceeding 1.6 cm / 0.63 inch. Please ensure compatibility with your window track before purchase. - Easy Installation : No additional tools are required for installation. Each lock comes with a hex key for hassle-free setup. Designed for horizontal and vertical windows as well as sliding glass doors. Note: These locks are not compatible with plastic window frames. - Versatile Applications : Ideal for a variety of environments, these locks allow windows to remain partially open for ventilation while ensuring safety. They help prevent unauthorized access by keeping both children and homes secure. - Safety and Air Circulation : By allowing windows to stay ajar, these locks improve air flow while offering peace of mind against potential intruders. Perfect for homes with children or frequent outdoor air flow needs.