Laboratory Bottle Spare Outlet Ring. Excellent laboratory bottles with screw caps, suitable for holding a wide range of laboratory reagents etc. These graduated bottles are made from borosilicate glass, with wide mouths and GL45 (45mm dia.) blue chemical resistant polypropylene screw caps and outlet rings for drip free pouring. Bottles and all parts are autoclavable. Caps do not have liners, as they are ‘bore-seal’, whereby the top of the bottle forms a seal against a rib/skirt on the inside of the cap.