it's hard to believe that as small as this hobby is, there are several different manufacturers making plugs, today. i'd bet there is a single manufacturer making them all and selling them to be re-branded. many rebranding manufacturers will make items somewhat individualized for different brand names by coloring them differently or using different colored seal material or something like that to satisfy the "brand" requirements from larger brand names, but the plugs remain physically the same from brand to brand. there just isn't enough volume to keep several different manufacturers busy making individual designs . there's also the fact that in todays manufacturing industry, shared technology has all but stifled individual design in favor of a single design that is known to work well in all situations. this is especially true in items of simple design with no or very few working parts.