Beware of the Craftsman 3/8" push button locking extensions. The 3/8 comes in a set of three (3", 6" & 10") part No. CMMT43355 (Made in Taiwan). At this time they have bad QC with profound locking problems. I had a set of the older USA made style with the black plastic sliding tab--the plastic button on the 10" broke off. I contacted Craftsman and they eventually got it right (see below) and sent a set of the newer style with the black metal push button (part number above). Unfortunately, the 10" locking extension would not lock on a socket 19 out of 20 times, and even then might pull off with a medium tug. When it was inserted into most sockets, the little metal button stayed retracted and did not pop up--depending on the socket, it was almost flush and other times it was half way up and did not lock onto the socket.
I had horrible problems with customer support sending 1/2" non-locking extensions (first 6" and then they ordered a 10"). They ate up over an hour of time correcting those mistakes so I wanted to avoid going back to customer support. The closest Lowes is 18 miles away but I was near one on Saturday so figured I would warranty it there. That's when I found out that this product line has serious QC issues.
Because I live far away and I was a bit suspicious, I didn't want to swap it out without testing each of the extensions. It's a darn good thing I did. Lowes was cool with it and they cut open the package. The 10" extension in the new set would not lock on either of the other extensions in that set. Fail. The rep tossed the new set into their return basket and said I was free to try another one. I grabbed a couple more sets off the floor. In the second new set I opened, the 10" locked onto the other extensions but the 3" and 6" would not lock. I mixed and matched between the old and new sets and thought I was good. It was not good.
After I got home, I tried the 10" extension on some of my sockets. It's hit or miss with under a 50% locking success rate. I tried it on several brands of sockets--a mix of old and new. When it locked, sometimes it would only lock on one of the four sides of the 3/8 input square. I then tried the 3" and 6" extensions on a bunch of sockets. Their success rates were higher but they didn't lock on every fifth socket or so. They also had times where they would only lock if inserted one way.
This was my first foray into modern SBD Craftsman. I was really disappointed with the tools and with the inept customer support. (The last time I bought a Craftsman tool was in a Sears store so that was AGES ago.) After this, I would much rather buy ICON than CMan for the ease of warranty exchange at the store. I bought some ICON sockets and wrenches on sale within the past year and haven't had any problems yet. However, there are no ICON locking extensions.
I am back on the market for good locking extensions. I read elsewhere that the Stahlwille ones are very good so I'm going to look at those. I'm also going to read up on the Protos.
[p.s. I got the old Craftsman locking set in the 90's. I don't recall them ever failing to lock on a socket (I've misplaced the 3" and 6" so can't test them ATM). I bought the set to work on my 92 300ZX. Once you leave a socket stuck on a sparkplug deep at the bottom of a tube, you buy a set of locking extensions. I still have the Z.]
