Ikea Lilla Children's Green Potty https://www.amazon.com/dp/B00BR2UF78/ref=cm_sw_r_cp_api_glt_fabc_WEGM612T4KHF6GY1G0RY?_encoding=UTF8&psc=1

We used this one starting at about 3 months. It fits well on top of a counter while we would stand behind him and support his feet and back. We just stopped using it at about 9 months because he got tall enough to put his feet on the floor and try to stand lol