what tip to use

Hello, Thank you for your question. Tip sizes are identified by 3 digits. The first digit multiplied by 2 represents the width of your spray pattern at 12 inches from the surface to be sprayed. The following 2 digits represent the orifice that the pain passes through in thousandths of an inch. The spray tip that was likely packaged with your sprayer is a 515. This indicates a 10 inch spray pattern and a 0.015 inch orifice. This tip should work well with most interior latex paints. With that said many paint brands will actually indicate an appropriate tip orifice on the paint can label. If you have further questions please call Graco Technical Assistance 1-844-241-9499