The set contains machined aluminum base with spindle and nipple, ram and case reinforcing sleeve. A 9/16" ID X 2 1/4" long tube (Stock #T214R) is placed on spindle, compressed with whistle comp and capped. The spindle leaves the correct amount of space in each tube to produce the best whistle pitch every time - no guesswork or measuring! Comes with instructions and whistle formulae. Tubes and chemicals not included (Potassium or Sodium Benzoate, sodium salicylate, and Potassium Perchlorate).