Patek Philippe Aquanaut 5167/5164 Steel Clasp, Factory sealed, unworn and unused original Patek Philippe Aquanaut 5167A/5164A deployant clasp in stainless steel.
If you have 5167/1A (bracelet model) then this buckle will allow converting your watch into the strap model 5167A.
The clasp comes in factory sealed plastic with sparing bars included.