ROCKBROS Electric Bike Sucker Bike Rack for Car Roof Auto-pumping Suction Cups Hold Over 250lbs Pull-strength No Unloading Front Wheel Design: Being different from the ordinary bike suckers on market, ROCKBROS sucker is to fix bikes through the handlebar and saddle to achieve installing the bike on the car roof. This design takes advantage of the thin wheel to reduce the wind resistance to keep bikes more stable. Auto-pumping Air Out Tech: The motor-driven suction cup can auto-extract the air in the suction cup more thoroughly and create a vacuum environment in the suction cup, so as to provide a higher differential pressure inside and outside the suction cup, which makes the suction cups attach to the car roof more tightly. Tandem Link Design: Handlebar cups and saddle cups are reserved an exhaust port to connect the motor-driven cup so that one cup can drive other suction cups to extract air out thoroughly and ensure the stability of the bike during the driving process. Front view after installation Tandem Link Suction Cups 1*motor driven extracting cup, 2*handlebar cups and 1*saddle cup, connected through tandem and parallel hoses, auto-extract the air in the cups out and makes them attach to the car roof more tightly. ROCKBROS electric suction cup bike rack for car roof Maximum Pulling Force: 250 lbs Specifications Secures 1 bicycle up to 45 pounds Mounts on any car, truck, or SUV Weight: Approx. 9 pounds（including package) Air-leak Alarm Included Electric Air Pumping Universal Application Much More Safer Easy And Quick Installation