Coarse, Medium and Fine foams which will make a very effective mechanical zone in your filter. Coarse and Medium are approx. 1" (25mm) thick and Fine pad is approx. 0.5" (13mm) thick. Use in any filter so water hits them in this order:

Coarse, Medium then Fine

That way the dirt particles in water will be filtered out using a graded system which will be most effective and will increase intervals between maintenance. 

Foams are 11" x 17" x 1" (430mm x 280mm x 25mm) 

Coarse foam is approx. 15ppi and medium foam is approx. 30ppi

Fine pad is approx. 0.5" (13mm) thick and is classed as 'firm' - it is easy to cut to shape