A Vanstone edge is best described as which of the following?

• A. the edge of a patented duct connector.
• B. a 180-degree bend (or hem).
• C. the same as a draw-band joint.
• D. the 90-degree flange on duct with companion flanges.

Answer: (D)

Vanstone edge is the 90-degree flange formed on the end of a duct section to accept a companion flange on the adjoining piece. This creates a bolted, sealed seam where two duct sections meet, giving a strong, airtight joint that's easy to assemble. It’s not about a 180-degree bend or a hem, nor is it about a draw-band joint or a patented connector edge—the key feature is the perpendicular flange that mates with the matching flange to bolt the sections together and seal them.