I've used Stoney Knoll too and they look just like Archmat screens
that were made in New Hampshire by a Navy Vietnam vet that I had the
pleasure of speaking to once. I couldn't get the screen rushed order
as he was visiting his mom with emphysema in Connecticut at the time.
Quite frankly the only difference I can see anyway is the Archmat ones
had a trowel holder (a small block of wood with enough space to take
the blade of a trowel. Does someone know the story? Is it the
successful succession of a design that was favored by us the consumer?
Or a spontaneous invention?

If you want a really good stationary screen for large volumes, Bruce
Fullem once (?) of NY's SHPO, designed one that pushes back after
every push you give it and works well at a stationary point, as it has
to be driven into the ground. I've used it on a Hudson River terrace
prehistoric site in summer, with 12 allowable C14 dates (might have
been as many as 30) and on the winter excavation of the West Point
Foundry "workers houses" thought 2 out of five might have been built
by Virginians , i.e., like the ones in Glassey's study of
architectural house "foot prints" in Virginia the two closest to the
foundry core) and with the four legged flexible steel with welded
hinges holding a screen box, will process six buckets of dirt at a
time! Once sold at another archaeology supply co. that disappeared, in
NYC, called "Archeon" I think, Joel Grossman, Ph.D. had one welded up
from Mr. Fullem's sketches.

George Myers