The material it's made out of Copper an Brass being the better materials but I like to have silver plated contacts as they don't tarnish so easy but copper will do you just have to clean it more often. IMO I feel the magnetic switches are better as they have a smooth fell. But not the ones like the original #19 mech had. The bigger the contact area the better too. After copper, brass comes Stainless steel and aluminum in last place for conductivity. The other thing to consider is like tmcase says smooth threads. Another I look for is being able to use different size batteries and if possible being able to use a kick board. I think you should be able to remove not just the base of the mech but the top as it makes it easier to clean and convert it to a Hybrid if you so choose or use a different type of top or in case the top's contacts fail. Today there are so many good clones you don't have to pay that much but you do need to go for a good one. Some clones are better than others. Go to a web site with reviews to check it out.