The side marked with "TEC1-12703" font is the cooling side, and the side without characters is the heating side.
Size:40mm X 40mm/1.57" X 1.57",Voltage(V):12V; Umax (V): 15.5V; Max Current (A): 3A,QMax (W) : 18W; Resistance: 4.0-4.3Ω.
Application: Can be used in CPU cooler, backup power and many other applications.Can also be used for DIY, do car drink warmer/cooler, reverse polarity, cool or heat in minutes.
Lead length 300 + 5mm RV standard wire single head.
Devices should be used in conjunction with a heat sink to avoid burned.