Is there any reason to get this in addition to craftsman sockets and a Snap On 1/4 ratchet?
YES. you're on a tool forum so, more tools is always the answer.
Lets look at the set closer:
1. It comes in a nice steel box with a blow molded insert and foam lid lining.
2. It has 13 shallow six point sockets from 4mm to 14mm including 4.5 and 5.5mm. The sockets are nicely satin finished inside and out. Each socket has smooth detent scallops on the square drive end. The sockets also feature 5pairs of ridges around the outside of the socket. These ridges are great for finger spinning and prevent the socket from rolling.
3. The extensions and shaft of the spinner handle are ruled in MM so, you can use it to measue things. The extensions are also flat on two sides to facilitate using an open end wrench if necesary. The extensions also have the ridges around the female square drive that are excellent for finger spinning and prevent rolling.
4. The ratchet features a fine tooth 2.5 degree action with quick release.
5. Accessories: the set also includes a universal joint, sliding tee handle and a spinner handle that has a square drive at top of the handle for use with a ratchet or an extension.
Conclusion: The set is well made by a popular taiwan manufacturer. For $20, I think you'd be hard pressed to find a better value in a 1/4 drive set. The only real downside would be the absence of a dealer network with warranty support but, I don't buy things for the warranty so, I'm ok with that.
You mentioned having a student discount in another post. With time and experience you'll learn that the best tool doesn't always come off a tool truck, and that there's more to life than weekly tool payments.
