SBM is Societe de Bains de Mer, the owner of a group of casinos in famous Monaco. The famous Monte-Carlo casino is a "cousin" of this Sun Casino.

You'll see it listed on the linked ChipGuide page below. It's denominated as 25 FR., the older French Francs prior to current Euro monetary system.

The chip isn't particularly rare, but still a nice one to have, and a good story chip, as it related to arguably the most famous casino / location in the world (Monaco / Monte-Carlo).

It's a nice gift to receive. Enjoy!

http://chipguide.themogh.org/cg_chip2.php?id=MCMCSC&v=809572519