Using the Jarhead(JH) to vaporize your Cannabis flower will allow it to go a long way. While smoking flower a good portion of the product is actually burnt away. However, using the JH captures all the vapor in the jar so you do not loose anything. Also you do not need to use as much flower.
The video below gives you a good idea of the amount of flower to use.
Rule of thumb is “Use enough flower that will fit on the top of a coin like a dime or a penny. Flower that is grinded works best, allowing a more even release of its vapor.
Check out this video: