This firm but breathable mattress engineered with baby's safety and comfort in mind is made to perfectly fit Stokke's Sleepi Bed (sold separately). Support level: Firm with breathable layers for safe sleep.Other features: The core and the mattress are both washable. Compatible with Stokke Sleepi Bed V3 and Stokke Sleepi Bed Extension V3 (both sold separately) 54.52" x 27.75" x 3.14" Polyester/Sorona?elasterell-p Core and cover are removable for washing Imported