Its the 1/8″ “slap” when the string drives the nock into the on position.
Ravin nocks function in the same manner. It should NOT require an 1/8″ of movement. An 1/8″ of movement would be very concerning.
Five thousandths of an inch (.005) movement, is more than enough, to turn the nock on or off. All that is required is to make or break electrical contact with one contact.
The complaint with the Ravin nocks is that the fit is extremely tight, making movement inconsistent at best.