The Fittings | Stuffing Box Set (4 Pack) includes four PTFE-based shaft packing rings used to seal the rotating wiper drive shaft where it passes through the vacuum envelope of VTA wiped-film evaporators. The stuffing box assembly prevents air ingress and product leakage at the dynamic shaft seal, maintaining deep vacuum conditions required for molecular distillation. Replacing the stuffing box packing during preventative maintenance is essential for sustaining optimal vacuum depth and separation efficiency on VTA VKL and VKS series distillation systems.