A split retaining ring for a connection assembly adapted for connecting an instrument or other device to a vessel, such as a pressure vessel. The connection assembly includes a base, an instrument or device, and a split retaining ring wherein the split retaining ring includes overlapping end portions. The split retaining ring also includes an annular rib adapted for engaging a ferrule of the instrument or device in order to substantially sealing engage the instrument or device to the base.

A split retaining ring for a connection assembly adapted for connecting an instrument or other device to a vessel, such as a pressure vessel. The connection assembly includes a base, an instrument or device, and a split retaining ring wherein the split retaining ring includes overlapping end portions. The split retaining ring also includes an annular rib adapted for engaging a ferrule of the instrument or device in order to substantially sealing engage the instrument or device to the base.

A coupler can connect one or more instruments to a robotic surgical arm. The coupler can include a base and an actuator. The base can be securable to the robotic surgical arm. The actuator can be operable to release or secure the stem to the base and the robotic surgical arm.