A seat (1000) may include mounting components (1054a, 1054b) that may mate with corresponding components on other assemblies. The seat may include one or more features that may rotate or move to provide for coupling to the one or more assemblies. Assemblies include, but are not limited to, a stroller, a bicycle adapter, a wagon, a booster seat, a camping chair, a high chair, a stadium seat/picnic table, a hiking pack, an infant carrier, a car seat, a booster car seat, or an airline seat.

A child booster seat assembly is provided and includes a base seat and an upper seat. A first seating area is formed on the base seat. A second seating area is formed on the upper seat. The upper seat is detachably installed on the base seat. At least one first guiding structure is formed on the upper seat, and the at least one first guiding structure protrudes from a rear bottom portion of the upper seat and extending along an installation direction of the upper seat relative to the base seat for guiding the upper seat to be aligned with the base seat when the upper seat is installed on the base seat.