Unit coil using the latest developed double-flanging structure of wide seam blue hydrophilic aluminum fin, advanced mechanical tube-expanding process, ensure copper tube optimally contacts with aluminum fin. Wide seam hydrophilic aluminum fin provide sufficient heat transfer channel for heat exchange, wide impeller provide uniformly air velocity environment for heat transfer. It makes the heat transfer more complete, which ensures the cooling capacity per input power of 42CT outperforms other similar products.