Coverage you need
- 75% kit: 1.75u right Shift, 1u right column
- Standard 6.25u spacebar and bottom row
- The knob needs no keycap
About the north-facing issue
With north-facing sockets, a Cherry-profile cap on its downstroke can touch the switch's upper housing before full bottom-out on some switch types, felt as a slightly mushy landing. Fixes: use OEM/SA/XDA profile caps, use long-stem switches, or simply test; plenty of GMMK Pro owners run Cherry profile without noticing anything.
Stock situation
Barebones GMMK Pros ship without caps, which is why this question comes up so much. Double-shot PBT in OEM profile is the safest first set: no interference concerns, durable legends, wide color choice.
How to read a kit listing without getting burned
Kit pages are optimized to look complete. The reliable method: ignore the title, open the image that lays out every cap with its size, and find three things: a 1.75u right Shift, four or five 1u keys for the right column, and your Enter shape (ANSI bar or ISO ell). If the 1.75u Shift only appears in a paid add-on kit, price the bundle, not the base kit. For sculpted profiles, also check that the right-column caps come in sensible row heights; some kits only include extras in one row profile, which looks odd stacked down the board's edge.
Lighting is side glow plus legends
The Pro lights from two places: per-key LEDs under the caps and light strips along the sides of the case. Opaque double-shot PBT, which is most of the quality keycap market, blocks the per-key legends entirely but leaves the side glow untouched, and plenty of owners run it that way happily. If you want lit legends, you are shopping a much smaller pool of shine-through sets, and many of the well-regarded ones are backlit ABS rather than PBT. Decide which you care about before falling in love with a colorway; it is the single biggest filter on your options.
Owner patterns after the first set
A pattern repeats in the community: the first set bought for a barebones Pro is a safe OEM PBT set, and the second, bought months later, is the expensive one with the colorway the owner actually wanted. Two lessons fall out of that. First, the safe set is not wasted money; it becomes the tester for new switches and the spare when caps go in the wash. Second, if you already know exactly which premium set you want and its kit covers the right sizes, skipping the intermediate purchase is cheaper than taking two steps. The sizes, not the brand, are what matter.