URSA keycap profile

URSA is our keycap profile for Topre and EC-compatible boards, designed by 23Andreas. Doubleshot, a spherical deep dish, and a row profile drawn from scratch rather than borrowed from the MX world. It exists because until it shipped, the options for a Topre owner were the caps that came on the board or a compromise. This guide covers the shape, which keyboards it fits, which kits you need, and what changes with batch 2. If you're not certain your board is Topre in the first place, Choc vs MX vs Topre shows you how to tell the stems apart, and Topre & EC explained covers how these boards actually work.

FK has spent years bringing more options to keyboard users, most of it in the low-profile niche. Topre was the obvious gap and the hardest one to fill. These boards are very specific, and getting a cap right for them takes expertise that doesn't transfer from MX.

We ran a Topre survey back in 2021 to find out whether there was anything there. What came back was how passionate that crowd is, and how different the market is from mainstream MX: a Topre board is already excellent unmodded, so there's none of the MX reflex to swap everything out on day one. The appetite for color and customization was real all the same, and nobody was serving it.

In 2023 we met 23Andreas. He had designed the URSA profile and came to us to put it into production, while we were already looking into a Topre-compatible profile of our own. That turned into a genuinely enjoyable collaboration and into the set you can buy today. More about him on his designer page.

The result is the first doubleshot keycap set ever produced for Topre. No manufacturer had made one before. Until then the realistic options were the caps your board came with, or buying a whole second keyboard purely to harvest its keycaps, which plenty of people genuinely did.

The clearest way to read URSA is against the two shapes most Topre owners already know: the standard Topre OEM cap that ships on most boards, and the taller Topre Hi-Pro found on the HHKB Professional HP. URSA sits a little above OEM and well below Hi-Pro, with a much deeper, spherical top surface than either.

URSA is sculpted, so each row has its own shape. The rows are numbered 1 to 5 following the usual convention: R1 is the function and number row at the top, R5 is the bottom row where the space bar sits.

The interesting decision is at the bottom. R5 is convex by default, which is non-standard: almost every sculpted profile gives you a dished bottom row like every other row. The reasoning is that you don't hit the bottom row the way you hit the alphas. Thumbs and pinkies arrive at an angle, across the key rather than down onto it, and a convex top meets them more precisely and more comfortably. If you'd rather have the conventional shape, concave R5 arrow keys are included as well.

The row profile was developed on an incline of 6 degrees, a good average across popular Topre boards. That's why it feels right on an HHKB, a Realforce and a Leopold alike rather than being tuned to one of them at the expense of the others.

Five decisions define the shape of an URSA cap.

• Spherical deep dish. The dish is cut as deep as it can go while staying continuous, so the surface is smooth under a fingertip but still has character rather than reading as a flat plate.
• Flat top edge. A bespoke choice: the rim around the dish stays flat instead of deforming into the walls, which keeps the cap structurally sound and gives the top a defined outline.
• Convex side walls. The walls bow outward slightly, in the spherical keycap tradition, which underscores the curve of the top surface instead of fighting it.
• Skirt lips. The bottom edges are extruded vertically, so the cap sits with a lifted, finished look rather than melting into the plate.
• Convex modifiers. The bottom row carries the convex touch area described above, with a larger front fillet for a smoother edge under the thumb.

URSA fits Topre and Topre-compatible sliders. Layout is the thing that varies, so some boards need the Extension kit on top of the base set to cover every key.

If your board runs Topre stems but isn't on this list, email support@fkcaps.com and we'll check the layout for you.

This is the part that trips people up, so it's worth being blunt about it. Base is the starting point for every board, and Base is simply the Alphas kit and the Mods kit together. Everything else is added on top.

• Alphas and Mods are also sold separately, if you only need to replace one half.
• Spacebar is its own kit.
• Extension covers the extra and unusual keys: the wider layouts, and the rotated 1.5u Ctrl on the Realforce 87U.
• Accents adds the contrast keys on the colorways that have them.
• Blanks is the same shape with no legends at all.
• HHKB is a doubleshot ABS kit made specifically for the HHKB, in the US layout.

URSA comes in five colorways: Black, Classic, Minicom, Blue and Red. Batch 2 will add new colorways on top of these, coming in Q4 2026.

Batch 1 caps are doubleshot PBT at 1.5 mm: PBT resists shine and holds its texture over years of use. Batch 2 moves to doubleshot ABS with a reinforced stem, the change that solves the breakage a small number of batch 1 sets saw. Both are 1.5 mm.

Doubleshot means the legend is a second piece of plastic moulded into the cap rather than anything applied to the surface. It goes all the way through, so it can't fade, wear off or wash out, and that holds for either material.

The HHKB kit sits apart from the colorway system: it's a doubleshot ABS set made specifically for the HHKB, in the US layout.

Batch 1 was the first URSA production run, sold originally as preorders. What's left of it is the stock on this store today. Two issues surfaced once it was in people's hands, and we'd rather you read about them here than find out later.

Breaking stems. Reported on less than 2% of sets sold. We shipped replacement keycaps to everyone who reported it.

Spacebar sound. Injection imperfections that slipped past several rounds of QC left batch 1 spacebars sensitive to how they're seated: insert one without care and the sound suffers. We wrote up the fixes in Technical issues update.

Batch 2 fixes both. The material moves to ABS and the stem structure is slightly reinforced, which solved the breakage and leaves the stems much sturdier. The spacebar mold has been updated to correct the sound. When batch 2 lands we'll offer a replacement spacebar to anyone who bought batch 1, shipping excluded.

We estimate batch 2 will be available to buy in Q4 2026, with new colorways and JIS support alongside it.

From the public announcement to the finished set took two years, and we wrote up every stage as it happened. If you want the long version:

• URSA Survey Results (October 2023): what Topre owners told us they wanted.
• URSA Group Buy Announcement (November 2023): the profile goes public.
• Preparing files for manufacturing (July 2024): legends finalised and files handed over.
• First molds are in production (September 2024): tooling begins.
• Samples Approved (May 2025): the shape signed off.
• Production Complete (November 2025): mass production wraps up.

Is URSA compatible with MX switches?

No. URSA was designed for Topre-compatible sliders, which use a completely different stem to an MX cross. If you're not sure which your board uses, Choc vs MX vs Topre shows all three side by side.

Is URSA compatible with my keyboard?

Check the table above. If your board takes Topre stems but isn't listed, email support@fkcaps.com.

Are URSA keycaps PBT or ABS?

Batch 1 is PBT. Batch 2 moves to ABS with a reinforced stem. The HHKB kit has always been ABS.

Are the legends dye-sub or doubleshot?

Doubleshot. The legend is part of the keycap structure, so it will never fade or wear off.

How thick are they?

1.5 mm, the industry standard for a high-quality keycap.

Is there ISO and JIS support?

JIS support arrives with batch 2. ISO needs new molds of its own and stays on the roadmap.

Will there be other colorways?

Yes. New colorways come with batch 2.

When is batch 2 available?

We estimate Q4 2026.

Do I need to mod a Realforce 87U?

No. The Extension kit includes the rotated stem keycap for the 1.5u Ctrl, so the board works as it is.