Plantronics BackBeat GO User Manual page 5

TRY IT ON
The right fit = the best audio:
For the best sound performance and
a secure, comfortable fit, be sure to
adjust the earbuds to rest gently in
your ear and drape around the back of
your neck. Use the provided fit kit to
find the eartip that works best for you.
For additional support, place the
optional stabilizer behind the eartip.
The loop of the stabilizer will fit snugly
into the back area of your ear.