Hello the 13 is the CFM so it can do 1300 cfm or 3 ton the 10 represents the heater kit 10KW. The B is the voltage 240 VAC there should be a Q or an R after this the Q is a 2.5 ton coil the R would be 3 ton. ( the air handler can do two sizes) the next letter would be a V for vertical or an H for horizontal installations. Let me know if you need more or want the spec. Richard.