Topeak has a huge design flaw with the bicycle floor pumps that use the TwinHead pump head - when the yellow lever is in the middle position, and the pump is put onto a tire valve, air shoots out of the opposite side of the pump head. When you push the valve lever into position the leak stops, but when you open the lever to remove the pump head, the tire loses air quickly until the pump head is removed from the tire valve, rendering the gauge rather useless. I contacted Topeak and they told me "this is how the head is designed". Buy from a different company.
Pumps that include this design: Joeblow Dualie, Joeblow Fat, Joeblow Elite, Joeblow Mountain, Joeblow Max II, Joeblow Sport II - probably some others I'm missing as well.
