Tune-o-matic

Tune-o-matic (also abbreviated to TOM) is the name of a fixed or floating bridge design for electric guitars.

It was gradually accepted as a standard on almost all Gibson electric guitars, replacing the previous wrap-around bridge design, except on the budget series.

It is still a signature feature found on guitars from the Gibson USA product line.

These bridges are also used on some archtop hollowbody guitars, such as the Gibson ES175D, which use a floating rosewood or ebony base (or foot) with two threaded posts screwed directly into it.

[1] Due to its symmetrical design, it's possible to accidentally fit the bridge on backwards on the two posts.

Unless the player wishes to completely reset the action and intonation, it is important to refit the bridge in the same orientation as before a string change, regardless of which way round it was to start with.