Inverted monotube. I'm used to it on my sports cars. As far as the ride quality, by far better than the factory Ranchos. The ride is smoothed out, body motion control is better, traction has increased and obstacle negotiation has gotten better (tested by climbing the rear of the truck over a curb). Later this week I'll see about load carrying capabilities since I still have more stuff to move from my old warehouse to the new. The ride is firm, but not harsh. By far a more refined damper. The Ranchos felt stiff and harsh unladen and bouncy and uncontrolled loaded down.