JR Packages [P] Ltd. Manufactures Heavy-duty Double Wall Boxes. JR Packages [P] Ltd. Is an ISO 9001:2000 registered company. Heavy-duty Double Wall Boxes is manufactured from heavy-duty 275# D.W. /ECT-48 kraft corrugated. Heavy-duty Double Wall Boxes provides greater protection and stacking strength. These heavy-duty double wall cartons are sold in bundle quantities and ship flat to save on storage space and shipping. These double wall cartons are twice the protection of a standard carton.