MEWANG Wooden Dog Stairs/Steps - Foldable 4 Levels Pet Stairs & Ramp Perfect for Beds and Cars - Portable Dog/Cat Ladder Up to 110 Pounds

Q: How much does this weigh?

I can't tell you what it weighs but my wife has no problem picking it up

Q: is this a good choice for a 90 lb Labrador with arthritis?

The steps are very sturdy and nicely constructed. I did not place the steps straight out from my bed so my 25 lb Cavalier fell off the side while trying to turn on the top tread. Also the treads are black and I could not see them in a darkened room. If you are using them in light it would be okay. It is nice that they fold up if you are using them to get in and out of a car. If you are using them in the house you might want to check out PetGear Extra Wide two or three steps. Either will hold you 90lb dog. With the wooden steps he will have to jump up each step a little.

Q: Will the stairs slide on hardwood floor

I would say no more than any other piece of furniture. There are rubber strips on the bottom of the legs which resists sliding but it will move when pushed hard enough. My 12 pound dog has not moved the steps which in on a hardwood floor.