B-Line B161SS4 Eaton series strut fittings and accessories, 3.18" Height, 2.5" Length, 1.62" Width, .56lbs, Steel, Two hole closed angle, 37-1/2 deg, Thickness 7/32 in, 9/16 in hole diameter, Stainless steel type 304

Holes are 9/16 inch diameter, which takes the standard 1/2 inch strut hardware, channel nuts and bolts. Bolts and channel nuts are not part of the fitting, so order them separately for both legs.

It is type 304 stainless steel, so it holds up outdoors, on rooftops, in wash-down areas and in damp mechanical rooms far better than plain or electro-zinc plated steel. For the joint to actually last, match it with 304 stainless bolts and channel nuts and stainless strut; mixing plated hardware into a stainless connection is what usually starts the corrosion.

Material thickness is 7/32 inch. That is the standard heavy gauge B-Line uses on its structural strut fittings, and it is what lets the bracket carry load through the bolted connection rather than just locating two pieces of strut.

Go by which side of square your brace falls on. A closed angle like the B161SS4 works when the two members meet at less than 90 degrees, which is the usual case for a diagonal kicker running back up to a wall or deck. If your members open out past 90 degrees, a closed angle will not sit flat on both faces and you want an open angle instead. The B161SS4 is fixed at 37-1/2 degrees, so if your slope varies from bay to bay an adjustable angle connector is the better call.

Solid type 304 stainless steel, not a plating or a coating over carbon steel. That matters for cut or drilled edges in the field, since there is no base metal underneath to start rusting.