Then, measure from the inside edge of your door, including the furniture, to the centre of the door, to find dimension B.

The pins of a standard cylinder are divided into top halves (also known as upper, master pins or wafers) and lower (bottom) pins. Measure from the outside edge of the door, including the furniture, to the centre of the door. This is dimension A.To ensure accuracy, measure the overall length and ensure that it equates to the sum of A and B. Measuring up for a new door Once fitted, the cylinders are held in place with a central screw, located on the face edge of the door. Remove this screw to release the cylinder. The ABS Avocet cylinder in our opinion is one of the best cylinders available in the UK, it has the highest 3 star 'Sold Secure' rating. To measure up for a new door, you’ll need to measure the door’s width and any door furniture such as handles or escutcheons.