This instrument can be used for counting numbers; measuring time and testing period, etc. The timer also has a new timing function called ?v0?0?. It is a specialized timer for Type J2125 series Air Track. This instrument can be used for counting numbers; measuring time and testing period, etc. The timer also has a new timing function called ?v0?0?. It is a specialized timer for Type J2125 series Air Track. Used item, it is sold as pictured, please STUDY MY ACTUAL PICTURES of this item NOT THAT GENERIC STOCK ONE. Do your research before buying to be sure it's what you need, there is a restocking fee for my items. If you have any questions, please contact me BEFORE buying, a signature will be required at time of delivery. Thanks Additional Details ------------------------------ Product description: This instrument can be used for counting numbers; measuring time and testing period, etc. The timer also has a new timing function called ?v0?0?. It is a specialized timer for Type J2125 series Air Track. This instrument can be used for counting numbers; measuring time and testing period, etc. The timer also has a new timing function called ?v0?0?. It is a specialized timer for Type J2125 series Air Track.