Vacuum absorption never have bubble. PVC core replace plywood in hull, stronger, lighter and more waterproof. The opened deck, convenient to repair and maintain fuel tank and other device. Wider deck. More placidly on water. Tubes optional: best PVC 0.9mm thickness from Korea, 1.1mm ORCA hypalon from France, Taiwan hypalon. Stainless steel: AISI 316D6, no rust. Resin and gel coat material: DSM and ASHLAND. Filling material in FRP: PVC foam plate to make the boat lighter, stronger, more waterproof. Documents: CE certificate. Written declaration of conformity for each boat.