Sterling silver in the collector sets, and silver clad for casino play. Not that many were actually used in play. $5 slots were very unusual 45 years ago. I think they were used on the BJ tables, if at all.

The sterling variety is marked Sterling. In my opinion, the casino play versions are considerably scarcer than the silver ones. Not that they always sell for more, as the silver content is worth $40+ these days, but you seldom see the casino versions for sale.

Here's a Harolds Club 5 that is sliver clad. It shows wear from somewhere!

Note that all the Harold's club $5 clad tokens were made with the correct city; some of the sterling ones were made with Las Vegas as a city, but many were exchanged by collectors for the corrected Reno version.