This extension chuck was just the ticket. This allows me to fill the tire's internal dual valve without having to physically force the internal valve stem. The device is of high quality and meets my requirements. Please note that this extension cartridge has an internal "check valve" so it cannot be used with a control actuator that opens and closes the air supply. That doesn't bother me as I use a separate calibrated pressure gauge to check that I've inflated the tire to the correct air pressure.