How thick is this floss? I have really "tight" teeth so I need to use ultra-thin floss or it gets stuck.

I wouldn't recommend. I have tight contacts and there were some spots where the floss shredded and I had bits of fiber stuck between my teeth.

Has anyone compared this with Coco floss?

I LOVE Coco floss. I decided to give Dr Tungs a try. The packaging of Dr Tungs is cool, but not as sturdy as Coco floss. The plus is it is made from eco friendly sources. The floss itself is very comparable. It has enough wax for it to glide, but not too much where all you feel is wax. I like that it expands - similar to Coco floss. The Caradamon flavor is refreshing. Much different than the Coco floss. It is not overpowering, which is nice. I will purchase both brands again in the future.

What type of material is the floss made of?

Polyester. Cotton is no longer used in floss as it frays and is harsh. Floss that claims to use bamboo fibers are also harsh and bamboo fibers and textiles are really considered rayon. Silk goes through chemical processes and needs to be threaded or else breaks frequently. Nylon is similar to polyester. Both are from the fossil oil polluters and doesn't biodegrades till 30 years or more although polyester can be recycled. Waterpiks have a limited reach.