The ear tips are replaceable soft silicone tips that cover the hearing aid receiver. They prevent ear wax from getting on your receiver and causing damage. Hearing aids are designed to be worn with ear tips attached. Do not attempt to insert the hearing aids into your ears without ear tips attached.
The Concha Sol™ is shipped with the medium (7mm) ear tips in place. The hearing aids come with an additional pair of 7mm ear tips and two pairs of 10mm ear tips.
Pick the largest size ear tip that fits comfortably in your ear and forms the best seal. If it feels like the device is falling out of your ear, the ear tip is likely too small for your ear. If it feels like you have to force the device in your ear, the ear tip is likely too large.