Yale Cylindrical Lock is a strong and durable lock to use while securing your homes or workplaces. It's a double cylinder lock that's keyed at both ends. It's a reliable, mid-level solution for the replacement of existing 'multi-point' locks on uPVC, aluminium and composite doors. Yale has been the brand behind locks of every design and function in over 125 countries. As one of the oldest international brands, today's Yale is among the best-known and most respected names in the lock industry, with millions of Yale locks in use worldwide. What size do you need?It is vital that you order the correct size cylinder for your door. To determine which size cylinder you require you must first remove the cylinder.1) Remove existing cylinder2) Put your key in the lock and open the door3) Remove the screw that is beneath the latch4) Turn the key while apply slight pressure to the opposite end of the cylinder. As you do so the cam will line up with the rest of the lock and you will be able to slide the cylinder out towards yourself. The key usually needs to be turned approximately 25ş clockwise or anti-clockwise.5) Measuring the existing cylinder locks and offer British Standard (EN1303: 2005) security for your home or workplace. The size you require is determined by the distance from each edge of the cylinder to the centre of the fixing hole.6) Measure from the end of the cylinder to the centre of the Fixing Hole, to give the first measurement (a)7) Measure from the centre of the Fixing Hole to the other end of the cylinder, to give the second measurement (b)8) If you measured 35mm and 45mm, or 45mm and 35mm, then the size you should choose is 35/459) Extra keys: 3 keys supplied as standard. Additional keys can be cut as a nonrefundable bespoke service