Plasplugs PLASHCF553 HCF 553 Heavy-Duty Plasterboard Fixings Pack of 30 Plasplugs original heavy-duty easy to use Plasterboard Fixings ideal for securing medium to heavyweight items in plasterboard. The multi-thread technology offers superior holding power. With an expanding barrel and contracting fixing with integral screw thread. Typical applications: shelving units wooden battens wall lights small mirrors. Drill Size: 10mm. Screw Size: No 8 (4.5mm). Pack of 30.