15-D4 Bromobutyl Rubber Stopper can seal the screw glass vial with about 11mm inner diameter of the mouth, then screw a plastic cap onto the vial mouth.
| Specification | Crown Diameter | Crown Thickness | Plug Diameter | Overall Height |
| 15-D4 | 15.5mm | 2.4mm | 12.0mm | 13.0mm |
