LED light turns from red to green when your trailer is at the proper depth for safe loading and launching. The Load Mate comes with an adjustable float switch that can accommodate any boat and trailer combination. The LED array is completely waterproof. It has a high visibility dome which is also impact resistant for long lasting use. The Load Mate is also available as a retrofit to existing trailer guide-ons. Complete kit includes boat guides and retro light kit. Easy to install.