The Apollo casing is made of a plastic material with no known allergens. The wrist and ankle bands are made of neoprene and polyester, and the metal loop on the band is powder coated stainless steel. The materials selected for the Apollo casing and the strap were chosen based on their prior history of being used in applications with extended durations of skin contact.
If you’re concerned about allergies, Apollo can be worn over a sock or piece of clothing to avoid direct contact. Apollo is just as effective when worn over a thin piece of clothing.