Bonnell spring unit or mattress inner spring unit, compressed packing. Used for assemble mattress, with various kinds of spring unit, the most popular series is 288,312,364, 3.0, 3.6... All production are made according to BS4637 and BS3173. compressed packing spring, compressed packing springs Packing material: veneer stripe and metal stripe Packing quantity: 16-25pcs/crate, according to the kinds of spring unit, and the requirements of the customer.