The size is around 44mm.
I don't have a huge or thick wrist, but the Lum-Tec's fits perfect.
44mm is a really great size for a watch. My smallest is a 40mm Seiko, the largest a; Hamilton X-Wind 44mm, without the crowns (3 pieces).
I can only say; try a 44mm (the V1 wears smaller) .. it maybe suprices you. It did for me
