Hearing aids question help?

im looking for hearing aids so that i can hear betta and play softball without guessing wat the coach is saying. i heard of one that so small a doctor has to take it out to change battery and i told my mom that would be the only one i would wear so wat is that call i heard on cic hearing aids and it has a string and is not wat im looking for.if i cant find it ill go with that but i want the doctor one first.