Hook Jargon: Anatomy and Abbreviations

~By: Lance Dean | March 12, 2015

Label of a Package of U301 Hooks

When a beginning fly tyer looks at a package of fly tying hooks they can become a bit confused.  So let’s take a quick look at the common abbreviations/descriptions we might find on a package of hooks.  The description on a package of Umpqua U301 hooks says “STREAMER, DOWN EYE, 1X STRONG, 3XL”.  What does all of this mean?  That is what I am going to write about today.  I will explain what this means to me when I look at a package of hooks.

Before we get into hook labels and sizes we need to understand the “Standard Hook” and Hook anatomy.  Gap size changes depending on the size of the hook, it gets wider as the hooks size increases.  The gap of a standard hook correlates directly with the hook length of a standard hook.  The length of a standard hook equals 2 hook gaps of the same size hook.  With the exception of the Barb, all hooks have the following:

• Eye
• Shank
• Bend
• Point
• Barb
• Gap
• Throat

Umpqua U301 Hook Anatomy

The Eye of the hook is located at the front of the hook. It is the loop that you tie your tippet/leader to.
The Shank is typically the longest part of the hook and is on the top. It is essentially the backbone to the fly. The shank varies in length depending on the type of hook.

The Bend of the hook is the part of the hook that is located at the rear. It curves to the point and helps keep the fish hooked after you have set the hook. The shape of the bend can vary with the hook type.

The Point of the hook is the sharp part of the hook that gets driven into a fish’s jaw when you set the hook.



A barb is a part of the hook that helps the hook stay in the fish’s jaw after the hook has been set. A lot of tyers fold the barb down with a pair of forceps, vise or pliers.This is done so that the fish can be released in a less harmful manner.The barb can make a hook difficult to remove from not only a fish but also yourself if you get hooked accidently.


The Gap is the area of the hook that is between the hook shank and the hook point. This area can vary in size depending on the hook.

The Throat is the distance between the back of the bend of the hook and the point of the hook.


The size of hook is measured off of a “standard hook” meaning the hook is ground zero for hooks.  Hooks are measured bigger or smaller based on the “standard hook” size.   It’s like saying “0X STRONG, 0XL”; all labels describing size are zeroed out.  The length of a standard hook is equal to two hook gaps.

The first thing you will find when reading the description on most packages of hooks is what the intended use for the hook is.   Umpqua intended the U301 hook to be used as a streamer hook. Does that mean that this is the only fly that a U301 hook can be used for, ABSOLUTELY NOT.  I not only use this hook as a streamer hook, I also use it for a few nymphs and hoppers as well. Other “intended use” labels include:

• Nymph
• Nymph & Streamer
• Dry Fly
• Caddis
• Scud
• Hopper
• Terrestrial
• Etc…etc…etc…

There are tons of different labels that can be given to a particular hook.

The next thing that can be read off this package of hooks is “DOWN EYE” this simply means that the angle of the hook eye is pointed down.  Two other ways the eye of the hook is labeled are “Straight Eye” and “Up Eye or Eye Up”.  On a “Straight Eye” hook the eye lays in-line with the hook shank and an “Up Eye” hook, the eye of the hook is angled pointing up.

The third label we read on this package of hooks is “1X STRONG”. This label is confusing to me.  So I am not going to go into great detail about it.  Just know that the wire used on a 1X STRONG hook is stronger than the wire used on a normal hook.  The opposite of “1X STRONG” would be “1X SMALL” meaning that the gauge of wire used is smaller than the wire of a standard hook.  I have noticed that this label in particular is different with different manufactures.  For instance TMC uses “Fine” and “Heavy” to define the gauge of wire used for their hooks.  The important thing to remember with this label is that “Small” or “Fine” means thinner gauge wire and “STRONG” or “Heavy” means thicker gauge wire.

3XL & 1XS Hook Diagram

The last label we read on the U301 package is “3XL” (another way to say this is 3 extra eye lengths long) this means that the U301 is three eye lengths longer than a standard hook length. Or three eye lengths longer then the length of two standard hook gaps of that hook size.  As an example let’s say we could  somehow find a way to cut the eyes off of three hooks and weld these eyes to the head of a standard hook we would have a 3XL hook.  The opposite of “XL” is “XS” or (Extra Eye Length Short).  The XS label tells us that the hook shank is however many eyes shorter than a standard hook. So a label stating that a hook is 1XS, it is 1 eye length shorter than a standard hook.

X-WIDE Hook

Another hook label designation is “X-WIDE”.  The TMC 2488 is an example of an “X-WIDE” hook.  The label on that hook says it is a “2X-WIDE” hook.  This means that the gap of the TMC 2488 is two eye lengths wider than a standard hook.  I don’t think there is a narrower gap hook than the standard hook so I do not believe that there is an opposite of the “x-wide” label. If there is I would not purchase them because I believe that if you go any narrower than the standard hook gap you will have difficult time setting the hook on a fish. The U301 used above does not mention this label, this is because the gap is “standard hook” size.  So if a label isn’t on a hook package it is probably because it is the standard size.

Other hook labels with their meanings are as follows:

BL	Barbless (TMC 100BL)
SP	Super Point (TMC 2499SP-BL)
H	Same hook as another but made with heavier gauge wire. (TMC 2488H)
C	Competition Style
BLJ	Barbless Jig Style

There are others labels but these are the more common labels that I have noticed.



I hope this helps take away from the confusion of trying to figure out what all those hook label abbreviations mean. When you’re just learning to tie flies hooks can be bit confusing especially when you are trying to decipher all the “Hook Jargon” that Fly Tyers use.

If you can think of any other abbreviations or "Hook Jargon" please share in the comments.

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