DESCRIPTION:
FLEX® is a special formulation derived from pure hops,
and its use is designed solely to provide bitterness to
beer. FLEX eliminates a significant amount of the inert
materials that come with the vegetative portion of hops
and hop pellets, and thereby reduces weight, handling,
and residual hop material that needs to be removed
from the wort during brewing. The significant benefits
from FLEX include its low viscosity, which allows it to be
measured and dosed easily in the brewkettle, and the
reduction of hop solids from wort, greatly reducing the
process loss associated with the absorption of wort by
the hop vegetative material.
FLEX is designed for dosage early in the brewkettle boil
and because the product provides hop alpha acids—the
same as those found in whole hops and hop pellets—the
isomerization of these alpha acids into iso-alpha acids
is still necessary by means of the boiling process in
the brewkettle.
Switching from whole hops or hop pellets to FLEX
will improve the utilization of the alpha acids for beer
bittering, and the brewer can take comfort in knowing
that the transition can be made with little or no effect
on hop aroma.

Read more:
https://www.johnihaas.com/wp-content/uploads/2018/04/FLEX-BestPractices_041518.pdf?fbclid=IwAR29KF1pvPFhJzrqdrcX6mO94zZOWg9LDL3y6aEvZyuuAdFj1JN6bgse1uQ