i have recently purchased a 2nd hand air arms s510 TDR regulated in .177, it's all set up & ready to go, my chrono CB-625 mk4 is in my room somewhere, can't find it so i have ordered a fx radar mk2 wireless bluetooth chronograph, when i find the CB-625 mk4 i will advertise it on here, it's never been used. won't be that long as i will be moving in the very near future. got 40 years of collected stuff to go through