Teat/bottle top and bottle don't always seal tight
Teat/bottle top and bottle don't always align for a tight seal. One pair of bottles we have are fine, the others leak when tipped. Learnt the hard way, once when bub was covered in milk when feeding and once when out and about and the bottle tipped, meaning we lost a whole bottle of EBM. If buying these bottles check the attachment of the bottle and bottle top/ teat before use.