Double Maddox rods are used in dissimilar image test that is used to assess ocular alignment. It can indicate the amount of torsion (twisting of the images) the patient has. It is composed of cylindrical rods that create a perpendicular line to the axes of the Maddox rods by using a light source.

Double-head stethoscope combines a brass bell and flat diaphragm chest piece that is used to detect a wide frequency range of sounds. Bell is designed to fit into smaller areas to easily detect faint, low frequency sounds and murmurs. Diaphragm transmits higher frequency heart and lung sounds.

Double-J closed tip urethral stent is an effective and important tool in the urologists armamentarium. Its design incorporated 'J' shaped curls at both ends to help hold the stent in place and to minimize migration. It provides excellent patient comfort and reduces stent encrustation.

Double strap respirator is a device designed to protect the wearer from inhaling harmful dusts, fumes, vapors and gases. It is used while working in dusty environments. It provides for a snug fit over the mouth and nose. Double shell design resists high heat and humidity. Smooth inner lining ensures wearer's comfort and acceptance for better compliance. It provides protection from small particles that can damage the lungs.