Fastener
Reference
will
help
you
identify
UST
(Unified
Screw
Threads)
and
metric
screws
by
simply
measuring
the
diameter
of
the
screw
and
counting
threads
over
a
short
distance.
Supported
UST
sizes
range
from
#0-80
to
2"-6
and
metric
sizes
from
M1.6x0.35
to
M55x1.5.