Remove the adjustment screws from the face of the grille and center the left guide rail on the left side of the window. Predrill the screw holes into the frame using a 5/32 bit. Some window gates use a top and bottom guide or track. If this is the type you’re installing, do the same, but center the track at the top of the window rather than at the left side. Repeat with the bottom track.
Secure the rail onto the window by drilling 1 3/4-inch wood screws into the mounting holes on the track and into the predrilled holes.
Slide the gate onto the left guide rail, then slide the right guide rail onto the right side of the gate. Adjust the position of the right guide rail so that it is centered on the window and predrill the screw holes.
Fasten the right guide rail by drilling 1 3/4-inch wood screws through the mounting holes and into the predrilled holes in the frame. For top and bottom track designs, stand the gate upright and remove the top and bottom anchor bolts. Lift the gate onto the tracks and re-install the anchor bolts through the gate and into the tracks to secure.
Make sure all screws are tight and the grille is firmly in place. Most window guard systems will include the proper screws, but if they don’t, use screws long enough to penetrate the window framing studs.
Adjust the position of the gate if necessary, and secure using the adjustment screws, if provided. Some gates may use a locking mechanism instead of screws. Cover the screws with steel inserts, if these have been provided, and tap them into place with a hammer. These inserts make the screws tamper-resistant.