A One Piece Toilet Seat is generally smaller than a 2-piece toilet. The tank is connected and sits lower on the bowl than on a 2-piece. Due to the smaller size, 1-piece toilets are able to be installed in bathrooms with less square footage that do not have as much space as a normal bathroom. The toilets use special toilet seat mounting anchors to secure the toilet seat to the bowl. One Piece Toilet Seat is a hinged unit consisting of a round or oval open seat, and usually a lid, which is bolted onto the bowl of a toilet used in a sitting position.