On most toilet seats, rear seat bumpers do not touch the toilet bowl until a person is seated. This gap, typically ¼ inch or less, is intentional, and is done to address any possible warpage in the seat or toilet. When a person sits, the seat flexes, all 4 bumpers touch, and the weight is evenly distributed.
The mounting posts are made of corrosion-resistant, medical-grade stainless steel, and very strong. When the posts are properly inserted into the back of the seat, the seat “locks” into place. Some of the post remains visible. The rear bumper gap does not put any radditional or unintended pressure on the mounting posts or hinges.