C – Parting bead. There are two parting beads positioned on both sides in the sash box, working vertically from prime to base involving the sashes. Each individual half segment of a Ventrolla parting bead consists of a draught-proofing system that faces the adjacent sash, forming a snug weather seal.  I just unlearned this https://mike-mozart81468.csublogs.com/43057186/the-greatest-guide-to-sash-windows