It is about battery motorised golf accessories, battery motors and control systems. I don't want to get technical - but more and more people are using motorised golf caddies and buggies. Chosing one is a technical area and a little knowledge before you buy can save a lot of trouble later. One of 4QD's principal markets is ride-on golf buggies.
Most American machines use petrol engines and the buggies are two or more person vehicles.
There are a few electric ones, but petrol is certainly more common. You may think that a buggy is little more than a chassis with three or four wheels, a couple of batteries, a motor and a seat. It invariably seems to take them at least a year of trial and error to get a vehicle which steers properly, isn't unstable and handles correctly. Buggies range from small, lightweight three wheelers up to more substantial four wheelers. The three wheelers are usually lighter, so are easier to get in and out of your car.