Need help choosing a strap on.

We need to get a new strap on. What is the best type I can use on him.
We want soft and flexible but we are not sure what type to get.
Does anyone know any brands that are good. I want to ram his ass and make him beg to cum lol
Also an idea of sites that sell the brands you recommend would be good.
Thank you in advance for your help
Vicky.