An in-line cooler for power steering fluid, 2.0 inches in diameter and 7.0 inches long. Fluid runs through it to shed heat before it goes back to the reservoir.
Brackets for it are in Howe's cooler bracket group (parts 1104-1001 through 1104-1003), and Howe has an installation PDF showing Adel clamp mounting.
Howe Performance part number 1104.