Please read the profile before purchasing. Important requests regarding transactions are stated. Your understanding and agreement with all of them are key to a smooth transaction, so we appreciate your cooperation. Used a few times, so there are minor scratches. Operation has been confirmed. Quoting from H P: This is an arm base that can be attached to the accessory shoe of housings and ports. It uses a unique locking mechanism for easy attachment and removal, and secure fixation. 5000 The head part can be replaced with a separately sold ball joint or GoPro mount, in addition to the standard YS type.