There are 3 types of IWS available - the basic, the standard and the pro. The basic comes with a 15 minute timer attached to the brain, it doesn't come with stands (although they can be added at extra cost) and uses 13mm/16mm pipework.
The standard comes with the advanced IWS minute timer allowing more accurate flood times, this is positioned remotely to the brain. It also use 13mm/16mm pipework and comes complete with stands for better drainage of pots.
The Pro system comes with the advanced remote minute timer timer, a large flood pump in the reservoir and double pumps in the brain unit for drainage, it also utilises 25mm pipework to allow for faster flood and drain cycles and less chance of blockages. Also contains stands for better drainage.