For the slim and grim. Invented in 1987 by Steve Byrne and originally brought to market as Lowe Balls, these have become the secret weapon of many aid and trad climbers. These little wonders will work in small parallel-sided cracks where the only other option is pounding a piton. Ball Nuts also work in pin scars and small flares where even modern micro cams simply won't fit. Since they weigh so little, many advanced trad climbers keep a #2 and #3 on their rack at all times.