Pack of 10 Rubber Grommets for making a water-tight seal for use in hydroponic setups and Dutch bucket growing systems, among other applications. These grommets make a water-tight seal with low cost 1/2" PVC pipe (known as Schedule 40 PVC pipe) sold at virtually all hardware stores in the USA. Despite the label "1/2 inch" this pipe has outer diameter=0.840" and inner diameter of about 0.6". To install the grommets, drill a 1 in hole in your bucket or other container with a hole saw or a 1" spade drill bit. Clean up any burr left over after drilling. Place the grommet in the 1" hole, then insert the PVC pipe. It will be easier to insert the 1/2" PVC pipe into the hole/grommet if you give the end of the pipe a little bit of a taper using a pocket knife or sandpaper. A little lubricant such as soap or saliva is also helpful. More details on the grommets: Style 1 Rubber Grommet, 3/4" I.D., 1-1/8" O.D., 3/32" Panel Thickness Inside Dia. (A)3/4" Outside Dia. (B)1-1/8" Overall Thickness (C)5/16" Panel Thickness (D)3/32" Panel Hole Dia. (E)15/16" Rubber Material Styrene Butadiene Rubber (SBR).