Both models sport Bluetooth 4.1 and feature a tethered - cable design rather than
the plastic neckband design that some companies use.
The earbuds feature
a plastic neckband design, though not exactly like the ones LG popularized a couple years back.
You've likely seen them; they feature a thick
plastic neckband which wraps behind the neck and rests on the shoulders.
The HD1 Free feature a «traditional» Bluetooth earbuds design — that is, they're a pair of ear pieces connected by a cable rather than the less popular
plastic neckband design.
The earphone come out of
a plastic neckband, but don't have a spring mechanism like some of the older models of this type.