1.625" x 3.25", 24 inches, 304 Stainless Steel Back to Back Slotted Strut Channel - Online Metal Supply
Brass channels for model makers
Pull 96mm C/C Channel Brushed Golden Brass - Modern Hardware | Modern Hardware
K&S 9886 Brass Channel, 0.014" Wall - 3/16" X 1/8" Leg Lengths, 1 Piece, Made in The USA: Toy Remote Controlled Vehicles: Amazon.com: Industrial & Scientific