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).