Aboistop Collar Refill Mustard Aboistop Collar Refills are suitable for the Aboistop Standard Anti-Barking Collar & the Aboistop Compact Anti-Barking Collar, as well as Masterplus spray collars. Aboistop Collars are the safe & humane way to control your dog's excessive barking. When your dog barks, the collar releases a harmless, painless spray which surprises the dog & interrupts the undesirable behaviour. In a few days, the dog learns to keep quiet while wearing the collar & concentrate on more normal activities. Aboistop has no side effects on the dog or his sense of smell, & as soon as you want to allow your dog to express itself as before (to guard the house, when you're staying in the country, etc.) all you have to do is remove the collar. Aboistop Collar Refills are also available in Citronella & Odourless.