Our advice
Parcel delivery: what exemptions are there for goods packed in small quantities?

List the technical characteristics - even the minimum ones - that your containers must meet, depending on the goods to be packed in them, in a purchasing specification. This will make it easier to check products on receipt, to change suppliers without compliance problems, to justify your good faith in the event of an accident involving your dangerous goods, and to check any regulatory changes that may have occurred when the ADR was updated.