• From master pulsation systems where each relay is activated a fraction of a second after the last one, stimulation pulsation systems electronically stimulate the cow to encourage her to release her milk. All pulsators and relays are fitted with “closed” entry nipples that connect to a fresh air line, plumbed to the outside of the building. These fresh air lines supply filtered air to each relay, preventing dust, insects, moisture and miscellaneous debris from entering the pulsation system.