24 different Kailh switches seated in a plexi glass block. You can take them out and replace them with different ones, and it comes with 24 clear keycaps. I think I need the bigger version with 50 switches as well !!
KPrepublic are the best. Great Kalih switch tester, very nice acrylic base, will definitely help you know what Kalih switches to buy for your next keyboard build. My tester came with 24 transparent blank keycaps, just as described.