# So, what exactly do I search for to find a #21 Hex Key Driver? **URL:** \ **Category:** Factual Questions\ **Created:** [September 1, 2013, 12:22am UTC](https://boards.straightdope.com/t/so-what-exactly-do-i-search-for-to-find-a-21-hex-key-driver/667701 "2013-09-01T00:22:36Z")\ **Posts on this page:** 3\ **Page:** 2
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [September 1, 2013, 11:50am UTC](https://boards.straightdope.com/t/so-what-exactly-do-i-search-for-to-find-a-21-hex-key-driver/667701/21 "2013-09-01T11:50:02Z")
> [@Gary\_T](#): > > I’ve been working with Allen wrenches for over 40 years. I can see one being called a “hex key driver,” but I have **never** heard of any sizing nomenclature for them other than the actual size in millimeters or inches. “#21” just doesn’t compute for this. I wonder if it’s a reference an “official factory tool” with a number used only by your company. I’ve begun to suspect that this is the case. After reading your post, I realized that the main toolkit the company assigns to classrooms is the: [Xcelite 99SM 23-piece Series 99 Service Roll Kit with Canvas Case](http://www.amazon.com/Xcelite-99SM-23-piece-Series-Service/dp/B000ITYL4O) So, I did some Googling and… in Xcelite land, a #21 is this: [XXcelite LN21 Recessed Allen Hex Socket Screwdriver, Amber Handle, 1/16" Head, 4" Blade Length, 6-5/8" Overall Length](Xcelite LN21 Recessed Allen Hex Socket Screwdriver, Amber Handle, 1/16" Head, 4" Blade Length, 6-5/8" Overall Length). So, in fact, it’s a 1/16th. :smack: > [@Gary\_T](#): > > I’m confused by the use of the word “adjust” here. You adjust something that has a range of settings, like a volume knob. It sounds to me like this is a matter of getting something tight enough. If so, I’d use the word “tighten.” You’re right, tighten is the correct word here. I was a PC tech before this job, so I don’t have any real mechanical skills or vocabulary. ---
**Author:** ![ombre12](https://avatars.discourse-cdn.com/v4/letter/o/d26b3c/32.png) [@ombre12](https://boards.straightdope.com/u/ombre12)\ **Post date:** [September 1, 2013, 2:21pm UTC](https://boards.straightdope.com/t/so-what-exactly-do-i-search-for-to-find-a-21-hex-key-driver/667701/22 "2013-09-01T14:21:52Z")
Old trick for getting more leverage on an L shaped Allen wrench is to stick proper sized nut driver (1/4 or 5/16 usually works) on the short end…will give you a lot of torque. Make sure you are bottomed on the Allen screw (hit with a hammer) and that your Allen wrench is good quality and the right size…or you will strip out something. ---
**Author:** ![Mr.Goob](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@Mr.Goob](https://boards.straightdope.com/u/Mr.Goob)\ **Post date:** [September 1, 2013, 6:14pm UTC](https://boards.straightdope.com/t/so-what-exactly-do-i-search-for-to-find-a-21-hex-key-driver/667701/23 "2013-09-01T18:14:05Z")
I do a lot of precision micro machining. Drilling and tapping holes as small as 0-80. (or 3/64") tiny screw heads that will strip out easier than screwing on a toothpase tube cap. Or so it seems when I’ve got way too much time into something and rush the job. Look up Wiha brand tools. Incredable selection of well made micro precision tools. Little more expensive, but a one-time tool box buy. Now I can only blame me not the tool. [Previous page](https://boards.straightdope.com/t/so-what-exactly-do-i-search-for-to-find-a-21-hex-key-driver/667701.md?page=1)