259Fx also complies with the latest USFS Specification which specifies phosphate only Retardants (and is listed on the QPL). The upshot of those changes were to make Retardant more friendly to acquatic species; but we still aim to exclude use around waterways due to acquatic sensitivity to ammonia. All other things, application rate etc remain same. That is, all Retardants that meet the QPL have equal Retarding efficacy. Coverage level on different vegetation types is what we seek to vary.
Material Safety Data Sheet (MSDS) here