The way it works is this: wires go through end caps which snap onto the main body, holding the junction inside. Sealant is then pumped in via the hole on the side, then the hole is plugged.

"A junction box is a means to contain electrical connections ... specifically for outdoor use (like the Amazon's Choice QILIPSU Waterproof Electrical Project Enclosure Junction Box).

Terminal-block rail assemblies are mounted and labeled in the enclosure so installers simply mount the junction box and ... stainless steel that contains a watertight and dusttight seal.