It’s cheaper on Amazon, not cool: https://www.amazon.com/TP-Link-HS105-KIT-Required-Assistant/dp/B06WD6Q8K9/ref=sr_1_1_sspa?ie=UTF8&qid=1544797135&sr=8-1-spons&keywords=TP-Link+HS105&psc=1
these are a good shape since you can still use the other plugs.
however, if you have one of those 4 or 6 way adapters that goes over an outlet this will block a lot of them.
We were able to lower our price. Buy ALL the plugs.