Polaris IPLMD3/0-3 3/0-6 Awg Polaris Insulated Multi-Tap Conn 3 Port (Dual Sided Entry & Mountable)
https://nsiindustries.com/product/3-port-black-mountable-pre-insulated-connector-3-0-6-gauge/
Polaris Black Multi-Tap Mountable 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.