I found the wpa listed as a accessory on arizers website and the new stems provided with the unit be different. The wpa(air 1/solo 1)has a larger diameter and smaller sized holes. It compressed my gasket a little bit and now my air 2 stem is a little loose fit. Still air tight i think... but you wont be experiencing the increased air/vapor flow with the current stock of the wpa or atleast when i purchases it, or what i received from arizer. Edit So this device was developed in canada? Was it tested in mexico prior to release? The actual heat up tempurature incorporates the glass stems heat retention.