The Skinny: Like the big brother YX510, the YX300 is a cellular repeater. It's dual band (1900MHz and 800MHz) but it's only 1/4 the strength. I like it better.
The Verdict: If you're in a small apartment this is the one to get. Instead of huge coil of full-on coax and a outdoor-mountable antenna, this one has suction cups for easy window mounting. The repeater sits at the end of 20 feet of cable, and I actually have similar performance to the YX510 in my little apartment, likely because the window mount makes it easier to place at elevation, and the weaker signal probably avoids causing signal feedback loops. The repeater has a mere six-foot radius, but I suctioned it to a metal cabinet, giving it some directionality. I think it works fine. It brought my iPhone's reception to -64db from -82, as long as I was within range. Bigger houses will want the YX510, though.