As far as I know there are many different lights .400 and .500 on the pro tree and "standard" tree.... I have the '02 Nhra rule book right here but I cant find the section) its just the time in between lights .... depends on where your at or what kind of event it is.... my dads got this box that you pick what tree you want, set your dial in , then it pre-stages you automatically and then you have a remote with a button to stage... then once the light goes you let off the button .... its even got a delay box built in so you can set that anyway you want.... it can be either "2" player or you against the computer.... (which is just your avg. reaction time) its kinda fun but it just goes to show that about 90% of drag racing is R/T.... I have played that damn thing for hours upon hours...