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Most orders ship within 1 business day.
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Purpose-built and carefully curated dive gear.
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Owned and operated by divers.
Machined from solid Delrin, this cap protects the fine, sensitive threads on the MK/Gemini head where the breathing loop attaches. These threads are easy to damage and tend to collect grit when the unit is packed with other gear. The cap keeps them covered during travel, storage, or long surface intervals - and also keeps bugs and other critters out of the head.
The cap is vented to prevent potential negative pressure when used with a head cover.
Fits MK/Gemini units released before November 2025. Newer production uses the bayonet connection, which is not compatible. No retrofit options exist for that version.
Sold per item.
This is not an official Fathom accessory.
Designed in California, made in China.
Fast shipping
Most orders ship within 1 business day.
Exclusive products
Purpose-built and carefully curated dive gear.
Small business
Owned and operated by divers.