About: http://webisa.webdatacommons.org/100878455

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	They are made with two layers - the top one is a felt like material and the bottom (non-skid) layer is rubber.
http://www.w3.org/ns/prov#wasQuotedFrom	focalprice.com