I cannot express the praise enough of TFTestkits. After researching both the TF-100 and K2006, it was the logical choice to buy the TF-100. While the cost was slightly more, it makes up for itself in the number of tests the TF-100 over the K-2006. I can't say enough positives about TFTestkits. The service was excellent and being I only live in the next state over the kit came in 2 days. Hope all the newbies check them out.