which is a ripoff frim the zegule one my wife got with her BC.
the idea is simular - a lop of bangee holds the mouth-pease - but the bangee is not directly connected or cliped to the D-ring. insted, it's sawn to a small rectangle of female velcro that is folded around the ends of the bangee. to connect this to the BC you use a small folded peace of thin webbing, folded, with male velcro sawen on the inside, and a small loop of cord sawen on the outside.
side view
%%%
===:::::::%---------
%%%
from above
=====####---------
= #### -
=====####---------
"=" is bangee
":" is female Velcro
"%" is webbing with male velcro
"#" is the outside of the webbing (no velcro)
"-" is a cave line.
the problem with the one-peace idea above is that when it's pulled the wrong way, the mouthpease will not pull out of the bangee. with the velcro, if you pull hard engouth, you will get the velcro to let go, and will be able to use the regulater. i've seen this happen in trainig, and you really don't want a setup where you may not be able to pull the regulater free from the bc.
BONUS: the bangee loop is ideal for keeping your spare O-rings. you slide the bangee throught the O-rings, and they are held very nicely between the bangee and the velctro.