An external HDMI monitor capable of receiving a 1080p30 signal is required to view the preview image and interact with camera menus. On-camera monitors typically also have useful tools such as histograms, waveforms, and focus assist. Some good monitor options for Wave are listed below.
Monitor
Size
Features
Atomos Shinobi
5"
Daylight Visible (1000nit)
Histogram, Waveforms, Focus Assist
SmallHD Focus 5
5"
Histogram, Waveforms, Focus Assist