Polaris IPL350-4 350 MCM – 10 AWG Polaris Insulated Multi-Tap Conn 4 Port (Single Sided Entry)
https://www.nsiindustries.com/product/4-port-black-multi-tap-pre-insulated-connector-350-mcm-10-awg/
Polaris Black Multi-Tap Connectors form secure connections between multiple conductors with a rounded design and UV-resistant insulation coating. Installs with a hex key and torque wrench, with no need for cover and taping.