The Vacutainer needle is double-ended: the inner end is encased in a thin rubber coating that prevents blood from leaking out if the Vacutainer tubes are changed during a multi-draw, and the outer end which is inserted into the vein. When the needle is screwed into the translucent plastic needle holder, the coated end is inside the holder.
Hearing aids are primarily useful in improving the hearing and speech comprehension of people who have hearing loss that results from damage to the small sensory cells in the inner ear, called hair cells
