Matrix Ground Mats. Design Flow manufactures in Chinaplastic Ground Mats (also known as Bog Mats) 2400 x 1200mm and 2400 x 600mm from recycled High Density PolyEthylene (HDPE) in a range of lours. Standard thicknesses are 10mm, 12mm and 19mm, and non-standard sizes or thicknesses can be manufactured.