You have successfully added from to your part list.
Crown Tuff-Spun™ Roll-3' x 60' Gray 3/8in Pebble
100% chemically blown, closed-cell PVC sponge mat available in two slip-resistant surfaces: pebble and ribbed. Economical anti-fatigue mat that reduces noise and breakage. Use for light to medium duty, dry areas. Thickness: 3/8".