I've used one for several years and don't leave my truck without it now. At this price I ordered a back-up.
http://www.cabelas.com/cabelas/en/templates/product/standard-item.jsp?_DARGS=/cabelas/en/common/catalog/item-link.jsp_A&_DAV=cat601130-cat601126&id=0079223517165a&navCount=11&podId=0079223&parentId=&masterpathid=&navAction=jump&catalogCode=9CC&rid=&parentType=&indexId=cat601126&hasJS=true
http://www.cabelas.com/cabelas/en/templates/product/standard-item.jsp?_DARGS=/cabelas/en/common/catalog/item-link.jsp_A&_DAV=cat601130-cat601126&id=0079223517165a&navCount=11&podId=0079223&parentId=&masterpathid=&navAction=jump&catalogCode=9CC&rid=&parentType=&indexId=cat601126&hasJS=true