Ivan found this and he says that they are competitors
for
In Vivo and In Vitro Isometric Force Measurements and
Isotonic Displacement Measurements
Four-bonded
strain gages form a rugged bridge which measures the strain produced
on a cantilever beam by the force applied. The housing is rugged
and the handle can be clamped. Gravity effects are reduced to one
dimension. High natural resonance is afforded by the cantilever.
There are no pivots — no friction.