Revolutionary 3M™ service life indicator technology.Deciding when to change gas & vapour filters can be a challenge. Some users change their filters only when they can detect contaminant odour, taste, or irritation inside the respirator, with the result that the harmful substance has already broken through. Others change their filters on a pre-determined schedule, potentially discarding still usable filters. The 3M™ 6051i & 6055i Organic Gas & Vapour Service Life Indicator Filters contain an easy-to-interpret visual End of Service Life indicator (ESLI) to help users in appropriate environments determine when to change their filters. This unique andinnovative technology is compatible with all 3M™ Half and Full-Face Masks and providesincreased confidence in protection, optimised filter use and peace of mind.