 While polydomes are typically cheaper than metal domes, they lack the crisp snap of the metal domes, and usually have a lower life specification.Polydomes are considered very quiet, but purists tend to find them "mushy" because the collapsing dome does not provide as much positive response as metal domes.For either metal or polydomes, when a key is pressed, it collapses the dome, which connects the two circuit traces and completes the connection to enter the character.