IKLF competition rule. Ranking System & Tiers category.
Each rank level has a minimum kettlebell weight requirement. If a lifter uses a kettlebell lighter than the minimum for a rank, they cannot achieve that rank even if their volume score meets the threshold. Example from IKLF documentation: 'If a lifter uses a kettlebell lighter than 16 kilos they would not qualify for Rank 1 even if they reached the total kilos requirement for that level.' The specific minimum KB weights per rank level could not be fully extracted while iklf.org is down.
See the interactive comparison on KETTLEBELL MONSTER™ for filterable views and more detail.