Panels come with 4 green joining clips per panel. A 1m Panel plus one of these 60cm panels creates the 1.6m width of the pen. Therefore if you want to create another gate at the front of the extension you will need both a 1m and a 60cm Panel. If you want to extend your pen by 60cm you will need two of these panels. If you want to extend it by 1m you will need to order 2 of the 1m panels. If you want to extend it by 1.6m you will need 2 of each size of panels.