For larger feet or for more coverage, this size offers great weight to relax or stretch aching, painful feet. Fits size 12-13 mens shoe size. Excellent for swollen, painful feet. NOTE: Use the small size for most feet. Ideal for therapy or comfort. The best size if there is swelling in your entire foot. Generously filled with golden flax, the baffled inserts will not allow the flax to flow to the bottom of the item...allowing consistent heat on top and bottom of foot. Easy slip-on, easy slip-off. Order Poly-Bags if using these to help soften sole of feet or heels if therapy ointment or cream is used. Poly-bags will also help keep the inner lining clean and sanitary for multi-person use.