FLX-SRGL-320 is an extension piece made of longitudinal seam-welded
plain pipe in 320mm length. The extension piece is applied for FLX-PLO,
FLX-PRO, FLX-PLO-P and FLX-PRO-P plenum boxes and used as an extension
of the spigot Ød1 for a supply/ exhaust air valve, e.g. equal to slab thickness.
