We have an infrared system that works great and the transponders are about 25.00 each or 5 for 100.00 its good fro club stuff and accurate but should you be in the midst of rolling upside down as you cross the line. (it happens ) it wont get counted it also can be less reliable if it is in direct sunlite. The amb system is the industry standard and in not 100% sure but is similar to nascar and form 1 systems it is deffy more reliable and that is 100% important at a big race where there can be NO mistakes