This macroline 90 degree swiveling elbow fitting available here are Norgren's nickel-plated brass style fittings (silver in appearance).
They're used on SP markers as well as some others.
They fit a standard 1/4" hose, and are threaded 1/8" NPT.
A layer of thread sealant paste is pre-applied, so you won't have to use threadlocker the first time the fitting is installed;90 degree elbow fitting is 360º swiveling elbows that can rotate around toward any direction.
Rated for C02 or regulated compressed air use.