Snorkel Mask
From Inkipedia, the Splatoon wiki
The Snorkel Mask is a type of headgear in Splatoon. It is a 2-star item produced by Forge and comes with the main ability Damage Up.
This item can be purchased from Cooler Heads for 3,000 Cash.
Appearance
It appears to be a green snorkel with a yellow tube pointing upwards at the right side. It has a black headband.