This is compact sized fuel pressure Gauge. Proper fuel pressure is critical for adjusting your carburetor or fuel injection, so don't rely on a poor quality gauge.
Liquid keeps pressure Gauge needle steady, which is extremely critical during engine operation.
AN6 fitting is Black Anodized Finish for Long Last, Strength and Durability.
AN 6 Male To AN 6 Female with twin 1/8" NPT Female Side Ports.