This is a 16oz Square Fuel Tank by Du-Bro.

FEATURES: Du-Bro fuel tanks were designed with toughness in mind!
It will not split or crack from vibration or pressure.
Can be used with pressurized fuel systems!
Comes complete with all of the hardware including Du-Bro's one-piece
clunk with fuel barbs built right on the clunk stem, your fuel
tubing will not slide off!
Can be used with either Glo-Fuel or gasoline (must purchase DUBQ0675
Gasoline Conversion Stopper).
Protruding front lip protects fuel lines from being crimped.
Filler cap fits over machined smooth neck of tank...prevents tank
from splitting and forms a positive leakproof seal.
Single or twin vent design for custom installation.
Soft brass tubes for easy bending.
Clunk fuel pick-up for even fuel flow.
Detailed assembly instructions with illustrations provided.