These little bumps are only for cover, under these there are the fixings.. For maintenance, you remove the little white caps, and with an English key, unscrew two dices.. Only this.. For maintenance of bidet siphon, sometimes is possible do without of unscrew the dices..this depend from the models.. For example, villeroy makes its ceramics without the white caps at left and right,but they have put these under the ceramics.. Thus you can't see them.. Anyhow It's only for design..