A yellow Labrador Retriever correctly negotiating weave poles at a dog agility competition. Similar to a slalom, weave poles are a series of upright poles, each about 3 feet (1 m) tall and spaced about 20 inches (50 cm) apart, through which the dog weaves. It is one of the most difficult obstacles for a dog to master. It varies from 5 to 12 poles at one time. The dog must always enter with the first pole to his left and must not skip poles.