Wear your solidarity on your wrist with the EFX Silicone Sport Wristband, which comes in three Harry Potter brands - Hogwarts, Slytherin, and Gryffindor. The wristband is elastic in silicone and easily to slip on, even with a bit of a stretch, from a range of 6-8 inches in circumference.
The material is smooth to the touch on the wrist, and doesn't cause any strain or pain (unless you are allergic to silicone, at which point please heed caution). The wristbands are wonderfully colour-coated for the silver/grey-and-green for Slytherin, with signature serpent emblem, red-and-green with lion mascot for Gryffindor, and the Hogwarts H wristband with the school's Latin emblem on it. Admittedly the set doesn't include Hufflepuff or Ravenclaw, the lesser popular Houses in the Harry Potter books, but the Hogwarts wristband is for one and all who feel a certain sense of home and familiarity to the Harry Potter series.
The EFX Silicone Sport Wristbands can be purchased here:
Hogwarts;
Slytherin;
Gryffindor.