Galvanized Window-Style Gecko Expansion Screw for Doors and Windows with Internal Expansion Sleeve. Designed for window frame fixation, the window-type gecko expansion bolt ensures strong holding power while being easy to install, durable, and reliably stable over time. Alignment, grip, and loosening issues in window-type gecko bolts are solved by guide ribs, adaptive wings and locking rings. Window-type gecko expansion bolts are used for window frame installations on concrete or masonry, offering quick, secure anchoring, high load resistance, and long-term durability.