The 2 knurled knobs do come out. Bottom leads directly to bottom of bowl,and is the only one going there. Top one connects bottom one just inside of `knob',then it connects to main shank, then to stem. The flow actually goes thru all three in an S or Z pattern. I only paid 5$ for it. It almost looks like a composite material,but it is wood. Will post better pics when wife comes home.