This high-quality mealworm feeder is a great addition to your bird-feeding setup. Whilst it won't stop cheeky squirrels from trying their best to steal the contents, the metal tube is designed to at least make it a great deal harder for them. The lid unscrews for easy filling and the perch tray at the base unscrews for easy cleaning. The diameter of each feeding hole is roughly 0.8mm so the feeder can be used for nuts as well.