Grommets and a drawstring rope have always been the traditional method for fastening a tank liner to the tank. The drawstring rope is a fine method for small liners (under 3 ft. in any dimension) but the rope doesn’t securely fasten the drop in liner to the tank flange. In larger tanks the weight of the solution can pull the liner into the tank a bit and have an effect on the quality of the fit. This is why we invented the Wittclip™ which securely locks the liner to the tank rim.
But are grommets even needed at all? A grommet is simply a ring that is welded into the liner. The grommet reinforces the hole where the drawstring rope passes through and it helps prevent the liner from tearing. However, the grommets used for this purpose are only 3/32 in. thick. In a thinner sheeting material the grommet provides the needed reinforcing strength. In a similar gauge or thicker, though, the grommet provides no extra benefit. That is why in a 1/8 in. or thicker liner we simply punch a hole in the liner where the Wittclip or drawstring rope is attached. There are no added benefits to the grommet so it doesn’t make any sense to pay for putting them in.