The Rox set contains 7 nuts in total, protecting a range of cracks from 6mm to 24.5mm, with respective breaking strengths between 6kN and 10kN, and weights from 16g to 42g The Rox nutset comes in a set of 7 different sizes and fit all small through medium cracks. Due to their large range these make a fantastic starter set. The fuller down the centre of these nuts plays two roles: firstly it reduces the weight of the stoppers, secondly the fuller helps the climber more easily set the nut into their chosen crack for a more secure protection whilst trad climbing. Rox nuts are colour coded on their stem for easy recognition of size. Kouba have been making active and passive rock climbing protection for 20 years in Czechoslovakia. As a company they specialise in nuts, cams and abalaks.