Yep. The base is just a separate. Like a donut.
Mine came with 2 plugs.
Dear, thanks for your attention. You can use it as a chair and please ensure that the ball chair is used in a safe environment without sharp objects.Please find our size chart on the listing webpage and choose the suitable size. Reach out if you have any questions or need any help, thank you very much.Trideer® Customer Satisfaction TeamCustomer-Oriented: 24/7 Customer Service12-Month Warranty & 30-Day Free Returns
They recommend a 55cm ball for your height. I’m 5’6 and the recommendation was 65cm but I went up a size because I have long legs, I’m glad I did.