The rapid x3 represents the pinnacle of safety light technology designed to ensure youre seen both day and night doubling the brightness of our popular x2 the x3 puts out 200 lumens in the front and 100 lumens in the rear featuring our most versatile system the rapid x3 easily mounts to almost any application including round and aero seatposts seatstays handlebars forks and headtubes with the optional spacer x accessory the x3 fits our flextight rear rack saddle rail and fizik sad