Important Information when choosing sizes. The OMEGA shock mitigating seat inserts need to have a minimum of 50mm of foam around the outside edge and 50mm of foam on top of them. This is vital as the foam around the edge holds the OMEGA's in place and gives the edge of your cushion a nice rounded soft feel. The 50mm of foam fitted on top of the unit is to increase the comfort. When you sit on a seat with OMEGA's inside you should'nt be able to notice that the seat contains OMEGA seat inserts. You should only be able to feel the OMEGA shock mitigating seat inserts working once you are hitting wave impacts.
Example for sizing.
A seat of 500mm by 300mm will need an insert closest to 400mm x 200mm.