Entropy International coin doors appeared most Bally and Williams games from around 1988 until the end of production. There are two types: two/three slot with one coin return, and a DBV (dollar bill validator) door.
Entropy doors usually have a distinctive diagonal “QUARTERS” insert (but I’ve seen this on other makes, too).
Around 1993, games transitioned to having a DBV. During this time, Williams used Coin Controls doors, then switched back to Entropy doors.
Later Entropy doors had ridges on the coin returns.
Entropy doors always have orange inserts.
I’ve listed these on the same page because they have a fair amount of common parts, particularly in the coin entries and return buttons.
Some parts are available from Pinball Life.