Sealife Sea Dragon flash Instruction Manual page 7

Attach camera (housing) to the tray. Carefully hand-tighten the
mounting screw. Do not over tighten!
Important:
Only attach the flash to cameras/housings with minimum thread
depth of 0.28" (7.2 mm) and using standard
Never force or over-tighten the screw, or you may damage the
housing seal and threads.
1 ⁄ -20 tripod type thread.
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