Ferret Nation & Critter Nation Accessories Kit Velvety, fiberfil cushion provides a soft and cozy shelf for rest and play Nation Accessory Kit1, Includes; (2) NA-SC Shelf Covers, (1) NA-HKS Small Hammock, Fits all 140, 160, & 180 cages. Custom designed to fit both FerretNation and CritterNationTM