I used to rig up stuff like plastic food containers with holes I made to try to keep connections dry until I found out these existed. I really like these! Have been using a couple for a few years now and no problems!
Pros: Locks cords together, no chance of accidental disconnection, water resistant.
Cons: Production quality looks low, service life could be reduced if used on multiple cords/times.
I've seen better, more expensive waterproof connectors, but these budget connectors do work. They're not water proof, but resistant, cannot be submerged. I purchased a three pack, to use in my coop, to connect heated waterers during the winter. Plug seal works as advertised, but I didn't trust it to keep its water repellency over the long term, so I sealed plugs with electrical tape. Meets my requirements for coop/run use.