Ferrule: 10 x 22 mm Security Stud : 16 x 25 mm Countersink: 15 x 4 mm features: Sash window security stop set Window can be locked closed, or in open position for ventilation. Set includes two security studs and four ferrules Countersunk ferrule provides a flush finish Available in a range of finishes with ferrule and stud matching Keys to be ordered separately code 75173 - see related products INSTRUCTIONS FOR USE Step 1 Drill 4 holes using a 10mm drill Two either side of window internally 100mm and 150mm above centre rail Step 2 Using hexagon key 90232 - see Related Products fit screws into holes so that the heads of the screws are flush with window frame. Step 3 Replace stud into screw using key If ventilation is required use top screw so that window can be opened slightly whilst still being locked