| Description | Accurately tests for nystagmus when rotated at 8-10 rpm. The optokinetic reflex allows the patient to follow objects in motion when the head remains stationary (eg, observing individual telephone poles on the side of the road as one travels by them | OKN Drums accurately test for nystagmus when rotated at 8-10 rpm.Four inch Drum is 20% smaller and measures 4” high by 6” diameter ( 10 cm x 15 cm) and weighs 19 oz (540 grams) |