Some customers may express concern that solid running surfaces don't provide enough traction for the animals, but there's no need to worry. (petbusiness.com)
Avoid foot injuries by selecting a wheel with a continuous solid running surface and not one with metal rungs. (caringpets.org)
With whip in full and powerful play, Arcaro avoided the muddy going on the rail, made instead for the solid running surface stretching in front of the vacant third stall. (si.com)