Top class headset with buit in headphone (one ear) and microphone.
Talking with persons that stand opposite are easy possible.
Environment nose is hardly absorbed (e.g. from start shoot, or spectators, loudspeakers).
When do you select the HS2-1:
For indoor use (e.g. timing room) when you do not have a lot of environment noise.
Extension Cable 165-03:
Optional is a 3 m extension cable available