On the Parker Vacumatic book by Geoffrey Parker,David Shepherd and Dan Zazove you can read on page 108 that the Parker Vacumatic Holy Water Sprinkler was an idea ( another one ) , of George Parker . The model was released in 1935 an according to the same authors: "Sprinklers literally flooded the Churches at Christmas".
For any unknown reason these Parkers are nowadays very scarce and for that reason (?) very sought after by vintage fountain pen collectors. I was fortunate enough to find two of these pens during my 20 years collecting. I hope you can enjoy them.