We recently hired an engineering firm to independently verify the design used for Stainless Steel ER40 torque wrench adaptors. It would give us the best baseline for a max use case given this is the largest adaptor we sell and has the most torque in normal use.
The results were that the deformation of the spanner tooth was typically less than 0.002” over 50,000 cycles at 125 foot pounds of force. The deformation is also well within tolerances for clearances and won't impact use.
The full report will be made available soon.