The "M" Plus Stem is made of stainless steel and features a square airport for easier air flow identification and a pivot style rocker on the opposite side for easy, manual air flow control. The Standard Stem has tactile grip in the tree-like, textured pattern. For a simpler, smoother look, check out the Classic style. The mouthpiece is tapered to 10mm and this stem will work with any DynaVap Tip. **This is just the stem - a Standard Condenser must be added for full functionality.