Size: Elongated The Mayfair Solid Bamboo toilet seats bring natural beauty to your bathroom. The natural bamboo design has a smooth finish that resists cracking and warping. Featuring classic non-tarnish metal hinges. From the Manufacturer Mayfair toilet seats are designed to fit all manufacturers round or elongated standard toilet bowls. Measuring for the correct size prior to purchasing your seat is very important. Using a tape measure, first measure the distance between the hinge post holes at the back of the lid area. The standard distance between the hinge post holes is 5-1/2-inches. Once you have determined that the hinge post hole distance is standard, next you'll need to determine if your bowl is round or elongated. To do this, measure from the front center of the bowl to the area directly between the hinge post holes. The dimension for a round toilet is about 16-1/2-inches. For an elongated toilet, the dimension is about 18-1/2-inches.