A restrictor for relieving the symptoms of erectile dysfunction by applying pressure to the corpora cavernosa. The restrictor includes a visual gauge for signaling a purchaser of adequate fit and/or potential overuse. The restrictor includes a surface treatment that changes temperature with color. The restrictor may be a rigid metal ring having a thermochromic surface treatment, such as a layer of liquid crystals covered with transparent glass or plastic. The restrictor may also be a flexible band wrapped in or made from a material dyed with a leuco dye or a dye including microencapsulated liquid crystals in suspension. The color change indicated by the thermochromic surface treatment indicates adequate fit and/or potential overuse.