10 Pack of Life Tubes or Slim Tubes They fit Siemens, Rexton, Signia, Miracle-Ear, etc. Open Fit BTE’S . Condition is New direct from the factory, not passed from reseller to reseller. I have a hearing center and order them for it as well. The NUMBER represents the LENGTH of the tube from top of ear to ear canal. Sizes go from 1 to 6 with #1 being the shortest and #6 being the longest. The color represents the side. RED = RIGHT BLUE = LEFT The best practice is to change these tubes every month – 2 months to keep the best sound quality! If you are unsure of what size or if these are right for you, please feel free to contact me and/or send a picture and I will try to help. The number and letter is printed on the end that is under or near the dome that goes into your ear. These ship first-class mail from my office in Mesa, AZ.