Polaris IT-250 250 Mcm – 6 Awg Polaris Insulated Tap Connector ( Dual Sided Entry)
https://nsiindustries.com/product/2-port-black-multi-tap-pre-insulated-connector-250-mcm-6-awg-2/
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.