SHOE MUST HAVE REMOVABLE INSOLE; Works best with big toe injuries that require added support in tighter fitting shoes as cleats and some casual /dress shoes without making the shoe too tight when the full insert isn't needed. RTP Carbon fiber inserts are MADE IN USA, Carbon fiber material is used in the building of airplanes, space technology, race cars and sporting goods equipment for the unique combination of low weight, high stiffness and tremendous durability. FOR PROPER FIT CARBON FIBER INSERT MUST be ¼ - ½ inch (approximately 1 cm) SHORTER than removable insert in shoe (because it is stiff), If necessary, measure in inches and use the ruler in the images to determine the appropriate size in centimeters; If in between sizes or half sizes round down to smaller size. INSERT MUST BE PLACED DIRECTLY UNDER THE REMOVABLE SHOE INSOLE OR UNDER ORTHOTIC; Used by used by professional, college, high school, and recreational athletes, as well as active people such as hikers, walkers, and laborers, recommended by sports orthopedic surgeons, sports medicine physicians, podiatrists, chiropractors, athletic trainers, and physical therapists. MAXIMUM STIFFENING INSERT WITH /MINIMAL FLEXIBILITY Carbon Fiber Insert SOLD AS A SINGLE PIECE, NOT AS A PAIR; HARD, FLAT CARBON FIBER INSERT can be used in EITHER RIGHT OR LEFT SHOE BY SIMPLY TURNING PRODUCT OVER; Best for BIG TOE injuries such as severe turf toe, big toe fracture, advanced hallux rigidus, best to use when having pain with daily activity.Item Dimensions LxWxH: 12 x 4 x 1 inches. Size: 29 cm Mens 12. Unit Count: 1.0 Count. Material: Carbon Fiber. Brand: RTP RETURN TO PLAY. Best Sellers Rank: See Top 100 in Health & Household. : B097NH9HFW. Manufacturer: RTP Return to Play. Date First Available: April 28, 2021. Item model number: A-MME-29. Product Dimensions: 12 x 4 x 1 inches; 0.71 Ounces.