I started using my old Littman Cardiology II stethoscope more and now had the black soft tip ear tips. The spring in the stethoscope was so tight, it pushed the ear tips too hard, and I never got a good seal. I used to have the gray firm ear tips, so ordered som more. Understand that I have a >20 year old steth with screw on tips, instead of snap-on, but i had adapters. I was surprised that the snap-on opening of the gray ear tips was so small, but figured out how to stretch the hole to ge tthem on. It took a lot of muscle power, but I had no other option.