Product Information: \nSET OF FOUR BAGS! When ordering you are ordering by the set. Therefore setting the quantity to 1 means you are ordering 1 set of 4 bags. Trolley Bags are a system of reusable shopping bags that are used to pack your shopping at the supermarket checkout. In one simple action the trolley bags system spreads out and rests on any supermarket trolley giving you a series of open and upright bags into which you can pack and sort your shopping with both hands. Gone are the days of using one hand to hold a bag open. The future is a simple system of bags that does the work for you.