Features: Freely control window width to prevent children or pet from climbing out of window. Exquisites workmanship, aluminum alloys frame and stainless steel screws that can be reused many times. Easy to install: there is no need to install extra tool, it equip a hexagonal key in each window lock, holding on the track by key control. It can prevent children from falling and protect safety of their family while improving air circulation. Suitable for family, hotel, schools, kindergartens. Specifications: Lock Body Component: Aluminum alloys Screw Component: Stainless Steel Type: Single Hole/Double Hole Color: Black/Silver Size: As Shown in the Picture Package Includes: 6set Window Lock note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to difference between different monitors, the picture may not reflect the actual color.