Select your Colour: White, Brass or Aluminium Extra Security for Doors Easy to fit, simply screw onto inside of door Screws provided - Please check length is suitable for your door See picture for dimensions A visor guard will protect you against the latest trend of criminals to try and "fish" keys by using hooks. Young arms that can fit through the letterbox are sometimes able to unlock a nightlatch. Thieves also try and evaluate the assets you have through your letterbox identifying valuable targets and making it more tempting to break in.