Applies to: TBT4-UDZ and the reviewed UD-ULTC4K version with three HDMI/DisplayPort groups. Not every hardware revision shares this layout.

The difference that changes the decision

RequirementTBT4-UDZUD-ULTC4K
Mac display pathsUp to two, limited by Mac chip and conditionsOne native group and two software groups
DisplayLink installationNot required for native videoRequired for groups 2 and 3
Video socketsChoose one per Mac output groupChoose one per numbered group
Advertised / certified host power100 W / 98 W100 W / 96 W

Plugable TBT4-UDZ: host, output groups and charging · Plugable UD-ULTC4K: native and DisplayLink display groups

For an M5 Air with two screens

A native two-screen arrangement can avoid installing display software. Plugable reports both products passed its M5 Air tests, so the decision should focus on screen paths, permissions, applications and the complete cable kit. The test report does not replace confirmation of your exact monitor modes. Plugable: reported M5 MacBook Air compatibility tests

For a Mac with one native external display

Additional native sockets do not remove that host limit. A software route changes how the extra screens are generated and introduces installation and workload conditions. Check those conditions before treating three available outputs as a reason to buy. Read the DisplayLink limits.

A repeatable setup check

  1. Identify the physical output-group labels on the actual dock.
  2. Bring up group 1 alone.
  3. Add the second group, with software installed if the route requires it.
  4. Check extension, the selected modes, sleep/wake and your normal applications.

If one numbered group works and another does not, trace that group’s native or software requirement before changing every cable.

Sources & scope

These instructions combine published references with our proposed diagnostic sequence. This setup has not been physically tested by Connect Your Dock. Manufacturer documents can change; use the exact model and scope linked below.

How we assess evidence