The most popular base key set is the default selection: Regular printed key set (US ANSI layout). The default is in the standard pearl/pebble color, though you can alternatively get this set in unprinted pearl/pebble (“regular”), black unprinted, blue printed, and dark gray printed. Click the magnifying lens inside a tile to see what each set looks like.
Mix and Match: Some folks want to mix and match key sets (dark gray and blue are a popular combination) but for that you’ll have to order a spare key set in the color you did not already select since there is no mix and match option available.
International Languages: There are many international key sets to choose from, all of which use the classic IBM Pearl / Pebble colors. For JIS, the shorter spacebar mod add-on is recommended, as many JIS users find the shorter spacebar preferable.
Recommendations: I strongly recommend getting additional key sets for the future because the key top texture wears down and becomes smooth/slippery with usage over time, just like the IBM originals (see this blog update entry for my wear analysis of IBM Model F keycaps). You'd definitely want to order spares if you anticipate using these keyboards for more than a few years in their peak physical condition, even long after the project has shut down and IBM XT Quality Model F new production key sets are no longer available.
HHKB 6 key set: typically includes a 1.5U size Delete key, 1U | key, 1.5U Caps Lock, 1.75U left Ctrl, 1.75U right shift, and 1U Fn (this will vary by international key sets; see the images for details on what each set includes). If you order an extra key set, please note that the HHKB set is not included with any spare base key set, so you will need to order the HHKB 6 Key Set store item. You do get one HHKB 6 key set included if you order a keyboard with split right shift, but it's always good to pick up spares of the most frequently used keys like HHKB (the HHKB set will correspond to your base key set). If your specific language is not specified, choose the "ISO Standard" option.
Front Print F Rows: These are available for various languages and add F1-F12 printing on the front of the number row of keys above the letter keys (pressing Fn+1 sends F1 to the computer, etc.).
What's Included: These key sets do not include extra, Front Printed, HHKB, or Apple-specific keys (split right shift, command/option, etc.). This means that all of the additional keys pictured in the base key set renderings will not be included if you order the base set. These other custom keys are shown for reference and are only available separately, either as part of the HHKB 6 key set, Front Printed F1-F12 set, or individually orderable through the Extra Keys store page. These extra keys are often indicated under a different heading like Front Print, Extras, Apple, etc. and are sometimes pictured with green or blue rectangles (these rectangles are of course not printed on the keys). If you order front printed keys, HHKB style extra keys, or Industrial SSK keys with your set, they will not replace any other keys you’re getting – you still get the full set, plus the extra keys you order. All 103 key sets include the space bar, space bar stabilizer wire and required 6 stabilizer inserts for the set, both horizontal and vertical inserts.
Compatibility and important terms: If you order the “full base key set” you get 103 keys so you can use the set on your other Model M or Model F keyboard as well as the new production ones, though the space bar is the Model M style so it will not work with XT/AT style space bars or Model F style space bars unless you make a custom wire or remove the plastic clips (not recommended) and attach the project's metal spacebar tabs instead. Individual legends are subject to change from what's pictured without notice and will vary based on available stock; they may not match these images.
Key colors (from left to right: Pebble, Pearl, Black, Industrial SSK Blue, 60% Dark Gray):
