If you have ever put together a European or Asian model you have probably experienced the need to have access to a “Phillips” head screw driver. I do a lot of mechanic work on my farm and I am a big fan of Craftsman tools. But even if you do use quality tools these American National Standard Institute (ANSI) drivers do not fit metric screws. They seem right, but they are likely to cam-out when the turning gets tough. There is a difference in metric and ANSI screws heads with a more rounded and slightly shallower center on the ANSI head. This was actually designed into the screw head so when you reached maximum torque your driver would in fact cam out. JIS screw heads are deeper and have amore crisp center cut. The problem is the ANSI driver just will not go deep enough to reach into the JIS metric head and that is where the issue of slipping starts. Metric screws in projects are almost always provided as the JIS (Japanese Industrial Standard – JIS tips have an extended tip and a more intimate fit with the screw head tip so it won’t cam-out). You will find that the ISO metric performs much better than forcing an ANSI standard tip into a metric screw. One of the best purchases I have ever made was to get a JIS set of screw drivers. Ask at your local hobby shop for one of these and I can assure you will immediately feel the difference. Here is a link to Moody Tools a great supplier of these JIS tools.