Yes, as a general rule you can store any kind of item — cardboard boxes, baby strollers, sports equipment, and more — with no size limit (a weight limit of 20kg applies; please separate your item into smaller pieces if it exceeds 20kg).
However, a select number of shops only accept suitcases and no other type of luggage — please make sure to read the store's reservation page carefully to check for any restrictions on the type of luggage that can be stored.
Pricing for non-suitcase items also varies by store location — please check the exact rate listed on the store's reservation page before booking.