The oval brass key disk is most likely either from the Royal Irish Constabulary of Dublin Metropolitan Police. This item certainly pre-dates the setting up of the Civic Guards in 1922. The ring states the following:
“Whoever finds this key or bunch of keys will be entitled to 2/6d on taking it to the nearest police station”
The back of the oval disk is stamped “27”
The second key ring is a bit later. It reads:
“Reward 2/6d Apply Garda Station”
The back of this circular brass disk is stamped with the numeral “4”.