When talking about the e-cloth® line, one of my customers made the observation: "No silver? But you've been heralding the benefits of silver all of these years.... What gives?" True confessions: he's right. Norwex puts silver into many of its products and it is a main selling point (it was even the basis for my URL - Norwexsilver.com). e-cloth® puts silver into its professional line, but not into its general cleaning cloths. So why not, if silver has anti-bacterial properties? The answer is simple - for most of us, the cloth's anti-bacterial properties come in the cloth already, and how we use it.... Let me explain...
The thinking around the silver in the cloth is about the 'resident' dirt in the cloth. When a cloth is highly 'grabby' like microfiber, and a user isn't always thorough in rinsing it with warm water when done, dirt and bacteria get caught and stays in the fibers. Silver in the cloth will inhibit bacteria growth. This is important when a cloth is used frequently, but not washed as frequently. The other two things that make it 'anti-bacterial' are 1) the quality of the microfiber (in which e-cloth® is slightly superior, even) as it picks up the dirt, and 2) microfiber's ability to dry out more quickly than other fibers, such as cotton. A dry cloth is also less hospitable to bacteria growth as compared to a wet cloth. There's a bit of a detailed explanation on the professional products description: e.g. http://www.eclothguy.
com/professional/e-cloth- professional-general-purpose- cloth-blue.html
So 'as you clean', silver makes no difference with respect to bacteria. In response to demand for silver, the e-cloth® developers began producing a 'professional' line. If you find that you rinse and hang your cloths well, and you launder them regularly, the general purpose cloth will be just fine. If you use your cloth very frequently, if it isn't able to dry out well between uses, and if you don't launder them regularly, the professional cloth may make sense for you.
In the end, adding silver to the manufacturing process will affect price. You'll find as always, though that e-cloth® always comes well under price when compared to Norwex products (see the comparison below, as of today's date.)
Norwex Enviro-Cloth - $16.99