They used to come in a little round tin, 100 in a tin.
They are little copper cases, look like a super-short .22, crimped over, copper casing, very loud.
They have an Acorn for a headstamp and are made by Rheinisch-Westfahlisch-Sprengstoffsfabriken - Werke Nobel.
German, just in case you didn't know.
Should be able to get them just about anywhere the healthy people swarm. They have to have the things for starting races, competitions and all those other important things.