The Carlisle Brass Double Phosphor Bronze Washered Butt Hinge is often considered more appropriate in residential properties due to the size of the hinge knuckle being smaller & more discreet than the knuckle on ball bearing hinges. For standard internal residential doors which are generally 35mm thick a pair of hinges is adequate; however, we would always suggest fitting 3 hinges per door as this will look more aesthetically pleasing to the eye. From a practical point of view the use of 3 hinges will help to overcome twisting or warping which sometimes happens to doors ove...