They don’t work beyond parting you from your money (at which they excel). If they get warm enough from the sun snakes will coil around them to warm up. They are useless for the purpose you bought them for.
There is even a topic about the useless snake repellers on this forum and is a worthwhile read:
@phb your alimentary canal is safe from any need to digest any calligraphy/prose/phrasing/grammar/writing…or hat for that matter 
