HBH GV435 : Very comfortable to use, lightweight, excellent sound quality (transparent to your hp sound quality), doesn't block sound wave to your ear canal (able to hear clearly in any enviroment)

HBH-IV835 : Hook-less as it uses our ear canal so support the unit, excellent sound qulity too,. The drawbacks > very low talk time (only 3.5 hours talktime ) causing your ears only able to hear one side as the other being stuck with this IV840 right to your ear canal. Not scratch resistant front panel as its made of acrylic plastic . Basically is meant for fashion statement not daily usage as compared to GV435.

Both of this model i have tried and tested it.