This handheld optical reader, developed for The GLOBE Program®, provides instant, accurate ozone readings using EcoBadge® TestCards (item# 653101). To determine the ozone level, simply expose a TestCard™ to the air for one hour and then insert it into the TestCard™ reader. The ozone reading is then displayed in ppb (parts per billion). Additional data with successive readings can be recorded and then uploaded into a computer. Macintosh®/Windows® compatible; PC cable with Macintosh® adapter, pack of 10 EcoBadge® TestCards, and instructions included with each TestCard™ reader. Requires 3 AAA batteries (not included).