Fig. 1. Components and dimensions of the noncontact repellent assay system. (A) Plexiglast barrier to separate assay into 2 equal-sized matched chambers; (B) the exposure chamber (subdivided into 2 smaller chambers); (C) section fitted with (or without, depending on test design) an outer screen mesh barrier; (D) screen barrier, measuring 3 3 10 cm2, constructed of fine mesh metal screen to protect the study subject from mosquito contact; (E) sliding Plexiglas plate that separates introduced mosquitoes during pretest resting phase before opening entire chamber for 3-min exposure period.provided a small opening with a 3-cm (1.2-in.) diam, closed with a split sheath of dental dam. This prevents free mosquito escape while permitting mosquitoes to be placed inside the chamber andremoved after testing. The 2 chambers allow a nonobstructive view of mosquitoes inside the assay system for direct observation of those that land on the screen barrier opposite either treated or untreated