Gunslinger CFDA Timer Standard Target Sensor (Bolt-On) $29
These sensors are constructed with highly dependable piezo transducers, they also have a foam box filler which nearly eliminates false hits recorded on the timer. Comes with 2 – 8/32 screws, with lock nuts, for secure attachment.
Note: Piezo transducers are similar to light bulbs, they may last a few months, they may last years. It is always advisable to have spare piezo transducers on hand, they only take a few minutes to change with a small phillips-screwdriver and pliers.