Tappabuco is a tire plug tool ideal for repairing punctures in tubeless tires. Designed to work as a end-plug for road and mountain bike handlebars, it can also be carried inside most Shimano and SRAM bottom brackets (it fits holes with an inner diameter between 15mm and 20mm).
While the larger, more common 3.5 mm plug is great for bigger punctures on mtb tires, a 1.5 mm plug is often enough for road/gravel tires: having both available is simply better.