Nectar Guard Tips slide onto the feeding ports on the underside of the cover. They’re a flexible membrane that opens easily for a hummingbird’s beak but flying insects can’t get through. Use with Aspects HummZinger Ultra, HummZinger Fancy, all Hummzinger High Rises, and HummBlossom Feeders. Will not fit Hummzinger Excel Regular, or Hummzinger mini's. Twelve nectar tips included in every pack. Made in the USA.