If I were you I'd keep your money in your pocket. I bought one from a chandler who is a really good bloke, put it on top of the a frame and it lasted 60 miles before all the nuts fell off and the plastic mounting snapped. When I arrivd at the launch site there were bits of my new light set all over the place.
Honourable chandler duly replaced and gave me some castellated washers to stop the nuts coming off second snapped its mount the very first journey so I just taped it to the flagstaff which is where it's been since. Winter project is to make one using the lights and wiring
Chandler tells me he's not come across a breakage before but then he is mainly an inland boats retailer so probably doesn't have many of his boats doing either rough weather or road miles.