Usage Tips:Boat cup holder made of Made of ABS plastic, The cup holder clip with anti- rubbers the grip is strong , mount to the boat rail, adjustable knob willl make the cup holder rock solid on the rail, you can put drinks in these cup holders and not worry about spilling all over . The cup holders are easy to install, just clamp and go without any tools and assemblies,no drilling needed and no damage to boat,mount on boat aluminum rail, pole or bimini top rail. Boat drink holder is simple, unique, durable and practical as , designed cup holder can hold different size bottles.adjustable clamp allows rotation , And with horizontal poles or any slanted poles, not just vertical.so it can be installed on different angle.with anti- rubbers keep the fixed inside , prevent drinks from spilling and falling downPontoon Boat, Bass Boat, Jon Boat, Jet . Boat rail cup holder can hold water bottles, coffee cups, beer, cans, glas and so on.Mounts to rails on boat, Can move cup holders to any rail.Suitable for Yacht, Pontoon boat, bass boat, Jon boat, Kayak and so on. Universal Drinks Holders are space inside can hold miscellaneous items. Suntan lotion, fish pliers, drinks, hand wipes, lures, Some little rubbish and so on. color:Black :ABS Package Contents: 2 x cup holder Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.