# Data and limits

URL: https://docs.sparklayer.io/developers/data

Reference for how SparkLayer stores extra product, customer and order data in metafields, and the recommended and hard limits on the data you send.

SparkLayer keeps some settings, such as a product's pack size or a customer's price lists, in [metafields](https://docs.sparklayer.io/help/glossary.md#metafields): extra fields on products, customers and orders in your eCommerce platform. Use these pages to look up the keys SparkLayer reads, and the limits to design your integration around.

- [Metafields](https://docs.sparklayer.io/developers/data/metafields.md): Every SparkLayer product, customer and order metafield key and type, such as `pack_size`, `rrp`, `price_lists` and `payment_on_account`, and how to auto-configure them.
- [Data limitations](https://docs.sparklayer.io/developers/data/data-limitations.md): Recommended and hard limits for SparkLayer data, including products, customers, customer groups, price lists, cart line items, addresses and discounts.