Watch Primer #02: Lugs

Lugs are an essential part of what makes a watch a wristwatch, as it would be pretty difficult for a watch to remain on your wrist without them.  The size and type of a watch's lugs can determine how a watch fits, whether it looks big or small on the wrist, how easy (or impossible) it will be for you to change out straps or bracelets.

Most lugs resemble those in the picture of the Omega Speedmaster above: tapered protrusions from the main watch case that line up to secure the watch to its band or bracelet, most likely through the use of an expanding lug pin like the examples below.

One of the original lug designs came from the World War II-era wristwatches which were pocket watches converted to be worn on the wrist (and thereby leave the wearer with the use of both hands).  A modern homage to this style of lug can be seen in the Panerai Radiomir:

    

Some minimalist watches, such as the Xetum Tyndall, feature a recessed "lugless" watch case:

And some watches have lugs designed to fit a particular strap or bracelet, like some Seiko 5 models:

  

Having specialized lugs like the ones above can limited aftermarket strap and bracelet options, but straps can sometimes be cut down to fit.

The lug's holes (designed to hold the lug bars) can either be recessed (like most of the watch examples above) or drilled, such as in the Citizen Stiletto: 

The width between the lugs can often determine how substantial a watch feels on the wrist.  Lug widths are usually even (e.g., 18mm, 20mm, 22mm, etc.) but 17mm and 19mm can also be found, though strap options are fewer.  If you purchase a watch with an odd-numbered lug width, be sure you like it on the strap or bracelet it came with, or do some advance research into the kinds of straps available in the same width.  

In my experience, though, the most important consideration when it comes to lugs is how long they make a watch look on your wrist.  A general rule of sizing is that a watch's lugs should not make it extend beyond the width of your wrist; this can lead to pie-pan proportions that will make it look as if the watch is ludicrously big, or make your wrist seem unnaturally thin.  Your maximum lug length depends on the diameter of the watch case and the size of your wrist, but for comparison's sake, the maximum for my 6-inch wrist is the 48mm tall, 42mm wide Omega Speedmaster Professional.