The Fix for the Dillon 550 primer cup problem! This will help keep your spent primers going into the cup and not on the floor. Just sit it on top of the factory Dillon cup and your done! It stays in place with the ridge design. I made it to have all of the curves in the right places to help keep those stray spent primers going where they should. Please note this is designed and 3d printed by me, so you will see printer layer lines, but over all looks great. Note: Factory metal cup not included. This listing is for the Blue part not the metal cup. Thanks for looking.