Babydan Olaf Wide Safety Gate in White. Installation instructions are available via the Onbox app (product code 5621) and they're also on the BabyDan website - if you find their manuals page and scroll down to find "BabyDan Olaf Wide Safety Gate".

Frames, poles, and end brackets included. You'll need some suitable screws and wall fixings.

I can post this in a cardboard box or you can collect in SE3 for free.