If your thinking about competing for the next few years as opposed to a "one off" I suggest you buy something that is approved for the Hans device posts,you can,t just screw them into any helmet the helmet must be designed to take them.The hot poop is that they will be compulsory very soon for all forms of motor racing.There have been several cases where guys have screwed the posts in to non compliant helmets and been sent home at scrutiny.You can no longer race at Q.R. or Lakeside without a Hans equipped helmet.Thought i,d better jump in and maybe save you some cash. Cheers