Size: 109*86*43cm WATERPROOF Your luggage will be well protected by 600D heavy duty PVC coated tarpaulin. All seams are heat welded rather than stitched with thread. It's thicker, more durable and waterproof than Oxford cloth with PVC coating or PU glue. Attach the two front and two rear attaching straps to the cross bars and four side attaching straps to the side rails. Feed the loose end of the front attaching strap under the roof rack bars and lock it into the buckle on the bag. Repeat the same procedure for all other attaching straps. Take up the slack in the attaching straps by pulling the loose ends of the four straps until the roof bagis securely attach to the roof rack. Connect the compression straps buckles. Tighten all four compression straps by pulling the strap ends against the bag contents. NOTE: Compression straps play a role of compressing the bag.Do not attach the compression. straps to the cross bar. CHECK THE LOAD: Pull and push the loaded bag after installation.If there is movement, tighten again if needed.Checkstraps routinely on the road and tighten when necessary.