| Description | Accurately tests for Nystagmus when rotated at 8-10 rpm. Drums are 10" high by 8" diameter. Light weight drum of professional quality with ball bearings for effortless spin mechanism. For use 24 to 30 inches from patient. | 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) |