As a general rule, netting comes in twine sizes. The smaller the number, the thinner the twine. A #24 is about twice as thick, and twice as strong as a #12 twine. A #36 twine is about twice as thick and strong as a #18.
Example: One company sells a 1500 series net. You might think they mean #15 twine size, right? Wrong. Their 1500 series is a #12. Their 2100 series is a #18, and their 4000 series is a #36. Their own numbering system is close enough to the popular twine sizes that people naturally assume a direct correlation. This is deceptive.
Twine #18 (2100 Series) The very minimum for batting cages. With light use may last 2-3 years.
Twine #24 Pretty good. Not commercial, but a decent net. With moderate use may last up to 4-5 years.
Twine #36 (4000 Series) A very good net. Universally considered commercial quality.
Twine #42 Many pro teams use #42 twine for heavy use. Great for commercial batting cage applications