The pricing isn't known but these look like sub-$150 motherboards. The duo draws power from 24-pin ATX and 8-pin EPS connectors, plus an additional 4-pin ATX power connector. The CPU area features 12-phase VRM and the boards have four DDR4 memory slots, two PCI Express 3.0 x16 slots (x16/NC or x8/x8), two M.2 slots (one 32Gbps and one 16Gbps), and six SATA 6Gbps ports.
TechPowerUp did a writeup of the rest of the featureset:
USB connectivity includes ten USB 3.0 ports (six on the rear panel, four by headers), and two USB 3.1 gen 2 ports (including one type-C port), on the rear panel. 8-channel onboard audio with a mid-range CODEC, and gigabit Ethernet with an Intel i219-V controller, make for the rest of the two. The Fatal1ty X470 Gaming K4 is slightly better endowed than the X470 Master SLI, in featuring a slightly more upscale onboard audio solution (probably ALC1220 vs. ALC892), Creative SoundBlaster Cinema DSP, RGB LEDs in even the rear I/O shroud, and Fatal1ty Mouse Port (specialized USB port with supposedly lower latency).