Fish hawk makes several different models. Some have a transponder that reads a sensor that attaches between the DR cable and the weight. I have my display mounted next my Lowrance. Depending on the model, they gives temp, and speed and depth at the downrigger weight depth. It gives the ability to monitor temp and adjust as needed in real time. Mine has temp and speed only. And reads at the surface, and at the weight.
I have scotty 1116 downriggers and even though I don't use a shuttle-hawk I put multiple "stops" on my cables, so I can stack easily. I run Stainless steal cable and to keep the stray electrical voltage from getting out of control, I made a "black box" to control any of that. So you can spend as much as you want or as little as you want. I've had a boat in my life, and have been Fishing for "blue-back" from about 1980. Some stuff works well and some only catch fisherman. Point is you need to find what works for you and, how it works best (speed, depth, leader, and size) and make it your own. Find an attractor and a leader combination that you can fish properly and perfect that!!