Universal 17mm/17.5mm Ball Head Bracket Base Adapter for Phone Holder 1/4" Thread to 17mm Ballhead Mount Connectors+D43MM/D66MM/D88MM 1/4" Magnet Suction Cup Expansion Mount. Aluminum alloy material, sturdy and durable; 2.1/4 universal screw hole to 17MM/17.5mm ball head;.
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