Amazon.com: 4K HDMI Multiviewer Switch 4x2 with PIP, PORTTA Quad Multi Viewer Seamless Switcher 4 in 2 Out with Toslink, 3.5mm Audio Output Support 4K 30Hz, 6 Viewing Modes, Downscaler for PS4/PC/DVD :
9x1 4K HDMI Seamless Switcher w/ Multi-View | A-NeuVideo, Inc.
4 x 1 HDMI Seamless Switcher & Multiviewer | SC&T
4K 4X1 HDMI Seamless Switcher with Multiview Processor - woxcon