I purchased this to use with Sonoff POW R2 WIFI and it fits perfectly. I do not intend to use it outside but it does come with a water seal string. It has 2 holes for cables and comes with 2 sealing valves with nuts to ensure that water is not leaked in. Sadly, the holes are a little on the small side so if using bigger cables then you need to check the dimensions. I was planning to use a 13 Amp extension but the cable was to thick so now using 8 Amp rated cable.