Big one, but get two! Put one on your boom (you can swivel the face around in the mount for when you are on port so it isn't upside down), put the second on your crew's arm!

Sync button is key!

Also, I've gone through a lot of these, the plastic "clip" on the strap will eventually break. I take it off (break it off) and stitch the two bands together. You'll thank me when the clip never breaks off and you loose the damn thing overboard....