Radz SDM Mast foot Windsurfing Radz SDM Mast foot 48mm SDM (standard diameter Masts) Mast Base is designed to to fit straight into the bottom of the mast or onto a drop on mast extension. accepts the Euro Pin with a push button on the side of it. This one has a black button not a blue button as per the picture Boardworx Windsurfing RadZ Windsurfing