This heavy duty tub mat from Walmart is terrific. The tub mat is made of commercial grade vinyl and comes in a standard size 16" wide by 30" long. The mat is extra heavy weight and easy to clean. it is recommended that you wash it with mild detergent before installation.
To install the mat in your tub you first run water to wet the surface of the tub. You then place the mat in the center of the tub and press down to engage the suction cups located on the bottom of the mat. You then fill the tub while stepping carefully onto the mat. Make sure that you press firmly in 4-5 places, holding onto the edge of the tub or grab bar, to anchor the mat to the tub. You then peel back the mat by releasing suction, rinse it and hang it to dry between use. Repeat each time you use the shower and hang to dry. The mat has been treated with an anti-mildew agent to resist germs, bacteria and mold.
This mat is white and has a design of raised concentric circles covering it from one end to the other. A great tub mat. I am unaware of the cost as it was purchased by someone else.