The holding tank with wheels and a retractable carrying handle. Stable thermoplastic rubber treaded wheels allow easy and reliable transport of the waste holding tank. LH/RH? Bench toilets are 'handed'. Left Hand or Right Hand is based on the position of the access door and this is to your left or right when sitting on the toilet. Their Cassettes / Holding Tanks are handed too. The C400-402-403 series are fixed as LH / RH but the C2-3-4 series cassettes are universal and can be reversed.