CO-05Pick the right fixing for your wallA CO alarm is light, around 150-200g, so most fixings will hold it - but still match the fixing to the material. Into a timber stud, use a wood screw straight into the centre of the stud, no plug needed. Into a metal stud, use a self-drilling metal-stud screw or a self-drilling hollow-wall fixing - never a plain plastic plug and never a wood screw, both strip straight through 0.5mm steel. If your fixing lands on plasterboard between the studs rather than on a stud itself, use a small self-drilling plasterboard fixing (a spring or self-drilling toggle) - it's light enough that a basic one will do. On solid brick or block, drill a 6mm hole to about 35-40mm deep, fit a wall plug, and use a 4x30mm screw. Through dot-and-dab, use a fixing long enough to reach the solid masonry behind the dabs, usually 50-60mm. On lath and plaster, aim for a solid timber lath if you can find one, or use a proper plaster/lath toggle fixing rather than a plug, which just crumbles the old plaster.