The 4 compartment Panino will work well if you want to fit in a larger item like a sliced bread sandwich (cut in 2) or a small roll in the bigger compartment (the 6 compartment classic is perfect if your child likes lots of little things instead). Both boxes are the same size, the amount of compartments internally (4 or 6) are the only difference. (Just fyi the inner seals unfortunately don't line up so you can't swap between a 4 and 6 compartment extra tray).
The Yumbox Panino is your lunch time go-to for kids of all ages (but especially up to about age 7/8). Pack a sandwich (crusts on), salads, sides and snacks. Prepare balanced healthy meals in minutes!