The G.R.A.P.P.L.U.H. is a wrist-mounted grapping hook and a personel gadget of Numbuh 1, worn on his right wrist. It works by firing a mini mic plug (via pipette bulb air compressor) from a AAA battery launcher. It then sticks to it's target, thanks to industrial-strength bubble gum, and the line is retrieved with a fishing reel. In the Kids Next Door 2x4 Technology Handbook, Numbuh 2 says that when Numbuh 1 started dating Lizzie Devine, he used the G.R.A.P.P.L.U.H. to pull himself into the air shafts at Gallagher Elementary School.