stair portions 20 the latter are shaped in a taper from bottom to top although not clearly visible in fig1 as mentioned above the sinuous shape of the lateral walls 36 facilitates the stacking the strength of the stair portion 20 is enhanced by the sinuous shape whereby deformation is reduced accordingly when stair portions 20 are nested one onto the other they will be more readily separated from one another if they do not deform still referring to fig7 packages of hardware are generally shown at h positioned in the cavity of the bottommost stair portion 20 the packages of hardware h include the handrails 22 and pool connectors 24 the uprights 26 28 if applicable and 30 the necessary fasteners for assembly and other components if applicable accordingly transportation volume is optimized moreover it is possible to stack other stair portions 20 in a reversed position in top of the first stack of stair portions 20 as shown at 20 u2032 for instance two stacks of four stair portions 20 on top of each other and positioned on a pallet is an optimal transport configuration the top two steps 32 of the stair portion 20 have on opposite sides holes for receiving therein the pairs of uprights.