What size is the jumbo liner? i need 20.75" x 15"x 24"

Dimentions: 24" x 18" x 15". It is for jumbo shipping cart. Fits cart perfectly square bottom.

Is this thick and heavy?? not thin and cheap like other PrimeTrendz.

Is it thick? no. is it heavy? no. is it strong & durable? yes it is.It is a thin lightweight fabric, but very strong & durable. I have had mine for about 6 months & never had a problem with it. it is a nylon or polypropylene type material, so it will last a long time.

do this fit tha cart with swivel metal wheels with extra basket

Yes. That is the cart that I bought.

Any suggestions for a good fitting liner for the Kirkland/Costco shipping cart?

I actually have one made for the Costco cart. I bought it with the costco cart. then one wheel on the Costco Cart broke and I tried to fix it, but I couldn't get the wheel to stay back on. One day I got disgusted with the entire thing and left the cart in a garage. When I came back a long time later the cart disappeared (probably because it had only 3 wheels). So now I have one repaired wheel plus a liner. So I wanted a new Costco cart but apparently they are not manufactured anymore (3 Costcos told me item discontinued).Okay so now I have a new cart and I need a really good liner about 17-1/2" X 15", waterproof. I still have the Costco liner. If you write me back I'll make you a deal...... but the liner that you want really has to be purchased with the cart. oh well.....Unless you know of a costco cart that I can buy --- but the cart I got is higher, which I need because I have a bad back. So that's the story.....Helene