Blue Anodized Aluminum Adapter (AN 815), -10 Male JIC 37 deg Flare To -10 Male JIC 37 deg Flare, Straight

That's right. This adapter lets you connect two male JIC 37-degree flare fittings of the same -10 size in a straight line. It's like a union for your hoses.

When you've got two male JIC hose ends or components facing each other in a line, there's no way to connect them directly. This fitting acts as a union in that situation, bridging the gap between two male -10 JIC ends so the circuit stays intact. It shows up in motorsport and performance hydraulic builds pretty regularly, anywhere you're routing lines between components that both terminate in male fittings and need a straight inline connection.

For a straight, same-size union, it fits that job. Both ends are -10 JIC 37 degree flare male, so it’s meant to make an in-line male-to-male connection where a female-to-female coupler is needed in the line.