I have used this white LED light for dozens of night paddle trips. It works well.
The light should really be renamed. Although the light does mount to the deck of a kayak, white lights are intended for use on the stern only. The light should be described by the mfr as "stern light" or "anchor light." Using the term "deck" with no other information might lead a kayaker to believe the light is suitable for use amidships or on the bow, which it is not.
The light works well. There is a small, clear cone on the top. Inside the cone is a spiral piece of white plastic. The white spiral piece colors the clear LED output correctly and distributes the light in a circle.
The unit is rated as waterproof and I have had no water entry problems. I exposed the light to spray, chop, and waves, but have not rolled the kayak with it attached.
The light body is fair quality plastic with a rectangular lanyard loop on each side. The light body fits into the separate suction cup base via friction. The base also has two lanyard loops. Although the friction fit seems quite strong, I tether both the light body and base to my aft deck bungees.
The light is about one foot high. I would prefer something a bit taller, but additional length would incur greater stress on the mounting, so the length may be a function of the relatively light mounting configuration.
I use lights as a safety mechanism. Sail and paddlecraft under 23' are not legally required to have running lights-either on the bow or stern.
I paddle a great deal at night and have been repeatedly endangered by power boaters traveling far too fast for conditions. I thus need the light to shine in about a 270 degree arc, with the forward 90 degrees blacked out. I use high quality electrical tape to block that section in an attempt to protect my night vision.
The light is packaged with "no name" batteries. I always replace such batteries with name brand or use rechargeable. I save all suspect batteries (and quality batteries that are nearly discharged) for non-critical use such as remote controls.
I would prefer that the light body, and the lanyard loops, in particular were a bit more substantial, but this is a minor issue.
The light has served me well and I recommend it.