A custom cell is a few grams lighter and a guarantee that the product is unrepairable the moment the tooling is retired.
The rule
Standard formats only, from at least two manufacturers, in a format that has been in production for five years already. A cell that is new this year has no track record for staying available.
What it costs
About four grams and three millimetres on a pair of earbuds. That is the entire price of the product being repairable a decade from now.
