LEBOO 3-Pack(48 inch) Tomato Cages Vegetable Trellis Plant Supports, Adjustable Garden Cages Tomato Plant Stakes for Vertical Climbing Plants, with 100 Cable Ties

Q: can you buy extra cnnecting arms?

When you purchase the set there is a connector that holds two poles together. So I don't feel there's a need to buy extra arms but you would have to buy another set and connect it onto the set that you already have. I hope that helps that's the best way I can explain it