So, I have been mountain biking for 20 years and finally bought a pump right for the job. What was I waiting for? The Chamber HV has a higher volume barrel so you can fill your tires faster. The gauge is calibrated for lower pressures since you are not likely filling your mountain tires to high pressure and accuracy at lower psi is pretty important. Pump head is good for either valve type and there is a convenient bottle opener at the top of the pump for a job well done (comes in handy around the shop!).