Cast iron block weights adjusted to M1 accuracy having fork lift slots and adjusting cavity. The 1000 Kg is flat topped and non-interlocking, the 500 Kg and the 250 Kg have the same footprint and interlock with each other. The 100 Kg (not pictured) is the same design as the 500 Kg and 250 Kg but has a smaller footprint so will not interlock with them.