The Control Collar is a specialized collar used to control something or someone. It can be controlled through a remote control.
In 1943, Red Skull placed the control collars on the Asgardian creatures that he captured through the Bifrost Bridge he found a way to access it and intends to unleash them upon the Allied forces and win the World War II. But his plans had been ultimately foiled by Captain America and Bucky aided by the Howling Commandos.
In present day, Baron Zemo placed the control collar he found in the ruins of a HYDRA base, on the Enchantress in his intention to use her to bring the armies of Asgard to Earth and make them under his control, but Thor had freed Amora from the control collar before telling the other Avengers to destroy the Norm Stones.