1. Marine Grade top vinyl for spa cover 2. Aluminium alloy c-channel for reinforce. 3. All shapes and 12 colors for chioce. 1 Our product line is spa cover ,outdoor spa cover, hot tub cover ,bathtub cover, swim spa cover, swimming pool cover ,lifter for cover ,PVC water pipe and related accessories . 2 Our advantage:1) Customize :No limited for the size &color&shape, all can be made to your order ...