Hi there. I bought this Powerline kit a year ago, I have the extender in my garden office and it works well.

https://www.amazon.co.uk/gp/product/B08LW5VPPV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

I now want to add a 2nd extender in one room in my house, but I am confused about the right product to buy. Presumably I don't need to buy another kit, as I don't need the adapter plug that connects to my router. What extender can I buy from Amazon that will work with my existing kit (i.e. it uses the powerline electric cable method, rather than a traditional wifi extender). 

Thanks