Dock Edge Solar PostLite - $48.88

Six pre-installed LED colors with built-in toggles let you change colors with the flip of a switch to differentiate your dock from your neighbors. Fits 1-5/8, 1-7/8, 2-3/8 and 2-1/4 posts as well as flat surfaces with included adapters. Installs in minutes without wires. Rechargeable, replaceable batteries included. Per 2. - $48.88