2-Port Clear In-Line Pre-Insulated Connector, 500 MCM-4 AWG
https://dev.nsiindustries.com/product/2-port-clear-in-line-pre-insulated-connector-500-mcm-4-awg/
Polaris Vision Tap Multi-Tap Connectors form secure connections between multiple conductors with a transparent rounded design and chemical-resistant insulation coating. Installs with a hex key and torque wrench, with no need for cover and taping.