Manual of Chameleon® Extenders 
With the Chameleon® Extender, you can have one brick collar and have the utility of two bricks. You can have more than one positive and negative contact point. Additionally, with the Chameleon® Extender, you can move your contacts and change the number of contacts to have optimal contact and best sensitivity for your dog. You can move the contact points as frequently as necessary to eliminate possibility of necrosis. Additionally, you can use the Chameleon® Feather Contacts which are compatible with the Chameleon® Extenders (and all Chameleon® collars) and give the best contact with flexible comfort.
• LARGE SIZE IS 31 CM LONG WITH FOUR ISLANDS ON EACH SIDE (THREE OF WHICH CAN ACCOMMODATE UP TO 3 CONTACT POINTS/PLASTIC SCREWS, AND THE END ISLAND THAT CAN SUPPORT 2 CONTACT POINTS/PLASTIC SCREWS) 
For the dog to feel something there must be at least one contact point in a negative island and one contact in a positive island. Islands that are mirror images of each other or adjacent to each other make up a positive and a negative island.
 
 
Manual of Chameleon® Extenders - 
With the Chameleon® Extender, you can have one brick collar and have the utility of two bricks. You can have more than one positive and negative contact point. Additionally, with the Chameleon® Extender, you can move your contacts and change the number of contacts to have optimal contact and best sensitivity for your dog. You can move the contact points as frequently as necessary to eliminate possibility of necrosis. Additionally, you can use the Chameleon® Feather Contacts which are compatible with the Chameleon® Extenders (and all Chameleon® collars) and give the best contact with flexible comfort.
SMALL SIZE IS 22,5 CM LONG WITH TWO ISLANDS ON EACH SIDE (ONE OF WHICH CAN ACCOMMODATE UP TO 3 CONTACT POINTS/PLASTIC SCREWS, AND THE END ISLAND THAT CAN SUPPORT 2 CONTACT POINTS/PLASTIC SCREWS).
For the dog to feel something there must be at least one contact point in a negative island and one contact in a positive island. Islands that are mirror images of each other or adjacent to each other make up a positive and a negative island.
For the Chameleon® Extenders for Martin System, we recommend purchasing a Charging Cable if you do not have one already.