On page 7 in the instruction manual you will find the part numbers of the two reagents you will need to measure CLO2 ppm. At
sensafe.com/exact-strip-micro-chlorine-dioxide/ you will read that "Each unit consists of a kit containing (1) bottle of 100 DPD1 strips & (1) bottle of 100 Glycine strips." "eXact® Strip Micro Chlorine Dioxide Kit for 100 tests Part No. 486633"
According to that description, you get both reagents when you order 486633. You can email or call the company to verify that information.
On page 10 of the instruction manual it tells you the range of CLO2 the meter will measure which is 0.04 - 7 ppm. Since 7 ppm is the highest it can measure, you will need to dilute your test sample with distilled water to be able to read 3000 ppm CLO2.