Keep in mind that your purchase is going to be delivered in a taxi, so use your common sense. If it needs to be moved using a trolley, it's too big. If it fits in a Toyota Prius without folding down the seats, you're probably ok.
Items like these are ok:
- Small electronics, laptops, accessories
- Clothing and fashion accessories
- Small office supplies (i.e. no desks or large furniture)
Large, bulky items are not ok:
- Large TV's
- Whitegoods e.g. dishwashers, washing machines e.t.c