Multi-layer mats are available in 30 or 60 layer versions. Each layer of the mat is fully coated with a particle grabbing adhesive, and an antimicrobial agent that prevents bacterial growth. Mats are constructed of heavy duty 1.8 mil (50 micron) low density polyethylene film. A printed number in the corner of each sheet indicates how many layers remain, and ensures at least one layer remains before replacement. These mats are made in and ISO 9000 factory, which means consistent quality is maintained from box to box.