[This is a referral to another site that sells these mapholders]
Autopilot PilotOne mapholders are lightweight, durable, and highly adjustable, designed specifically for adventure racing and mountain bike orienteering. They feature a 360-degree rotating corrugated plastic board, secure aluminum handlebar mounts (31.8mm/35mm), and a clear, waterproof, Velcro-sealed cover.
Setups come in Standard, Tallboy, and Angleboy for both 31.8mm and 35mm handlebars. The weight for the 31.8mm standard set-up is 292 grams (0.64 pounds).