Do searches for power-jelq, power jelq and maybe PJ. There has been quite a bit of discussion here on it in the past.
I have a home made Power Jelq and find it most useful for warming up and for doing sort of jelq squeezes — where I get an 80-90 percent erection and clamp down tight around the base, pulling outward towards the head as I do. I also use it to do bundled stretches — twisting the dick 90 degrees or so and pulling outward.
The power jelq is easiest to use with the rollers horizontal, so it emphasizes the top and bottom of the shaft. Targeting the sides, with the rollers vertical, takes some practice.
Unless you’re feeling rich, you should do a search here for how to make a home made PJ before you buy one online through the link at the bottom of the page.