I recently got my hands on a double-cup trombone mouthpiece from a bulk mouthpiece purchase on ebay.

CUP IS ENGRAVED:
"SPECIAL"
(HENRI SELMER PARIS emblem)

WHERE SHANK BEGINS:
1
MADE IN FRANCE

CAN ANYONE TELL ME ANYTHING ABOUT THIS MPC? AGE? VALUE?

It's terribly small in diameter (a good bit smaller than a 12C) and the 1st cup is very shallow and then sharply drops into a sharp narrow V-shape cup that leads straight into the throat.

The rim and inner cup are gold-plated...severe wear on the gold plating on the rim. The shank end is perfectly round, but shows signs of normal wear, and has a soft inward roll or bevel.

I can only assume that it might be an Alto Trombone or maybe even an Alto Horn Mouthpiece.