This is a juicer that was very popular in the 1980's into the 1990's. Insert the end with the teeth into an orange, or grapefruit, etc..., and twist until you completely pierce the skin. Now remove the juicer and in the bottom end will be the skin. Remove that skin and reinsert the juicer all the way inside and this time squeeze the citrus fruit. Out of the small hole will come forth the seed free juice.