The Baltic Snaplock first appeared around the same time as the Snaphaunce in the mid 1500's. The first Snaplocks were similar to the Snaphaunce with a separate battery. It was different from the Snaphaunce in that the Snaplock had a manual pan cover.
The Swedish at the turn of the 17th Century had modified the Snaplock to have the one piece frizzen as pictured above. Since the Snaplock never had a half cock, a novel safety feature was made utilising a screw that could turn the frizzen 90 degrees while still keeping the pan covered.