Other designs I have seen  have the spent primers boucing off of the stock primer arm, causing the primer to fly off into many directions.
My design helps to stop this problem of the primers not going into the press.
It helps but still not 100% of the timePrimers go down the catcher into a standard 1/2″ ID tubing found at any hardware store.Catcher simply slips into the bottom of the press.Note you will have to drill a hole in you work surface for the tube to come through.Note: Press and tubing Not included , 
This auction is for the primer catcher only.Will only with with multi ribbed style as shown in pics