As Sophie says - Perthshire late 90s.
This was a design that they introduced late on primarily to cater for the tourist market. The factory and shop in Crieff was on the tourist trail but many visitors would not want to buy, even the bottom end standard weights, as they would be seen as too expensive just as a souvenir.
This range, available in both red and blue backgrounds, were cheap to produce and were the cheapest weights available in the shop and it was hoped that visitors would buy these.