Apply Spirit gum or mastic to the inside edge of each ear and also your own skin, wait a minute and then press together firmly. Ensure skin is clean and dry before fitting.
I have tried many types of elf ears in years of LARPing and this set is the best. They represent true value and quality which is not easy to find. They accept make-up to blend in to your skin tone and look so real! I met my second wife at a gather while wearing these.