Batch numbers are required in most cases and can be found in the following places:

Soft goods: smallest tag or label on the underside of gyms or inside bags

Electrical: batch / serial number will be on the base

Drink bottles: date code shown as a clock dial on the base

Other hard goods: date code shown as a clock dial, usually on the base

Trunki date code on inside wheel arches

Baths: code on the base