Health insurance companies apply a sub-limits clause in the policy to control claims payment. It is basically a cap on the insurance claim and represented as a fixed value for specific diseases or treatments. It can also be a percentage of the total sum insured. The limit is usually applied to certain conditions like cataract, piles, tonsils, sinusitis, kidney stone removals, hernia treatment etc. although this varies from insurer to insurer. To know the full details, compare insurance online for best coverage.