I liked the small size and the convenience of connecting the cable. Cores are marked with the required connection UPDATE! I only had to replace one of my batteries because it overcharged and burned out. I bought 2 of these controllers, one for my 12v starter battery and the other for two 12v batteries linked together to power my 24v outboard trolling motor which runs during the Peak sun can supply 36 volts, so such a controller is needed. The second unit I bought for my 12v starter battery seems to work fine but I'm concerned about it.