The reason we at Blockley manufacture rim bands, rather than sourcing what is already produced, is because often the available rim bands are feathered in thickness at the edges. We find this unacceptable since their material used goes hard over a period of time and these thin edges act like razor blades slitting the inner tube. They are also often a dark fairly inelastic material.
The Blockley rim bands on the other hand are made from a softer compound and the edges are square cut at the full thickness, which stops this problem occurring. This level of attention to detail (as with all our products) really is important. Rim bands are only necessary in the wheel well of wire wheels, where exposed spoke heads are present. Insulation tape is not adequate! (this also goes hard and cuts the tube), so always use Blockley rim band.