I haven't bothered buying one of these things neither for my phones nor my display key.
I put my phones and display key in the pocket yet I put my wallet and other keys in the other pocket . Phones seem to get along well with the display key .I have not seen any malfunction at all.
Mont Blanc's is high quality item but if I had to buy a display key I would not pay premium for it just because it's a renowned pen maker's product
