Common backing and non-slip features include rubber or vinyl backings, PVC-foam or polyurethane backing, suction cups for tub/shower placement, and explicit non-skid or PVC textured backing to help keep the mat in place.
Many flat bath mats are truly flat or low-pile (less than 0.5"), while some offer a medium pile (about 0.5"–1") for a plusher feel.
Common sizes range roughly from 26.75 to 36 inches long and about 14.5 to 20 inches wide, depending on the style and intended use.
Mats specified for tub or shower use include teak bath mats and embossed or perforated vinyl/TPR/rubber mats that provide drainage and often include suction cups or other non-slip features for stable placement inside the tub or shower.
Some flat bath mats include bacteria-resistant or anti-mildew treatments, drain holes to reduce mold growth, and non-skid or PVC backing to improve footing and safety.
Many flat mats are designed to drain well: woven or perforated surfaces allow water to pass through, and these styles typically dry faster than solid-surface mats.