These specially designed weight stack adapter plates can stack 2-3 high Will stay together during home gym exercise Best design on the market. Patent pending Do not drop on hard floor Shipping to Alaska, Hawaii, Puerto Rico, Guam, Virgin Islands, and APO/FPO addresses or PO Boxes Ader durable 2,5lbs and 5lbs add on adapter work on most machines as long as the 2 guide rods are 5'' apart from center to center, fit most of Marcy, Body Craft, Body Solid, Multi Sports, and Master Fitness weight stack system.