Not postmarked, but it is an old style linen card. I can only guess at these handled surf craft, and I'm going with cork and painted canvas. Similar to an old life preserver. Cork sheets were commonly used for insulation before the advent of spun glass insulation and polyurethane foam. The linen (textured) postcards were mosty made from 1930 to 1945, but some also came later. The bathing suits vary, but some are belted. The belted suits are found in the same time range as the linen postcards. One kid has a rather baggy suit, but he could have borrowed that from a bigger person. Plus kids are more likely to wear "hand me downs." Keep a look out for a postmarked version of this card.
