Drag will slow you down when you are racing against the clock. A proper fitting time-trial helmet can save a cyclist up to a minute in a 40 km time trial. A fully vented normal helmet is the least aerodynamic helmet you can ride in. For riders looking to reduce their time in a time trial, a long-tailed aerodynamic helmet is faster than a short-tailed helmet. Another feature to look for in a time-trial helmet is that the tail fits directly over your back. One of the disadvantages of a long-tailed aerodynamic helmet is the drag it can cause if you are having to turn your head which you need to do when racing in a peloton. For those who want a more versatile aerodynamic helmet, a short-tailed helmet will give you an advantage without causing that extra drag when you turn your head. Short-tailed helmets can be worn to your aerodynamic advantage in a road race or criterium. Tour Cycling offers multiple Lazer aerodynamic helmets. The Lazer Tardiz is designed specifically for the bike leg in a triathlon. The Tardiz has the aerodynamic advantages of a short-tailed TT helmet but it allows the rider to deliver water into the helmet to prevent overheating which a triathlete can experience when going through a long distance triathlon. The Wasp Air is a shorter-tailed version of a long-tailed all out TT helmet. The advantages of the Wasp Air are the Advanced Turnfit System that allows the rider to fit the helmet exactly to the head. The Z1 Fast and Blade Fast helmets have a mold plus cover which provides aerodynamic advantages because air will flow smoothly over the helmet.