tip:
if you are getting one..consider 2 like cindy, if you can afford it.
one for inside that is just for inside with light color wheels. some of the black ones can make marks. using it just inside will insure that you don't get little rocks in the tires that can scratch floors. plus you won't track any dirt inside.
*this tip is from a friend who learned the hard way on her wood floors.
oh..if you have access to sams...they have them.
you can order online if they don't have one in stock.
www.samsclub.com