The Shroom, just like a mushroom has a flared head and a slimmer shaft. Also known as the Headmaster Senior this one measures 8½ inches high of which 7½ is insertable. The head is a whopping 4¼inches wide 13 inch diameter, and the shaft is 2¾ inches wide, which is about 8½ inches around. The toy is made with firm PVC and whilst it is fairly firm but flexible.