A product manifold for use with a portable oxygen concentrator, the product manifold comprising: a body; a first product port, a second product port, an accumulator port, and an output port; a flow path fluidly coupling the first product port, the second product port, the accumulator port, and the output port; a first control port, a second control port, and a third control port fluidly coupling the flow path; and a first solenoid valve assembly, a second solenoid valve assembly, and a third solenoid valve assembly; characterized in that: the first, second, and third solenoid valve assemblies (144, 146,148) are secured to the body of the product manifold adjacent the first, second, and third control ports (138, 140, 142), respectively, by a corresponding snap fit connector (150, 152, 154); wherein the first solenoid valve assembly comprises a first housing having an opening facing the first control port, a control element being disposed within the first housing, the control element being shiftable between a first position and a second position relative to the first control port, and the product manifold comprises a biasing element and a control element guide having a bore and being disposed in the first housing, the control element being at least partially disposed within the bore of the control element guide, wherein the control element guide includes a first portion and a second portion, the first portion disposed adjacent the opening, the biasing element disposed between the first portion of the control element guide and the body of the product manifold to bias the snap fit connector between the first solenoid valve assembly and the body of the product manifold. a body; a first product port, a second product port, an accumulator port, and an output port; a flow path fluidly coupling the first product port, the second product port, the accumulator port, and the output port; a first control port, a second control port, and a third control port fluidly coupling the flow path; and a first solenoid valve assembly, a second solenoid valve assembly, and a third solenoid valve assembly; characterized in that: the first, second, and third solenoid valve assemblies (144, 146,148) are secured to the body of the product manifold adjacent the first, second, and third control ports (138, 140, 142), respectively, by a corresponding snap fit connector (150, 152, 154); wherein the first solenoid valve assembly comprises a first housing having an opening facing the first control port, a control element being disposed within the first housing, the control element being shiftable between a first position and a second position relative to the first control port, and the product manifold comprises a biasing element and a control element guide having a bore and being disposed in the first housing, the control element being at least partially disposed within the bore of the control element guide, wherein the control element guide includes a first portion and a second portion, the first portion disposed adjacent the opening, the biasing element disposed between the first portion of the control element guide and the body of the product manifold to bias the snap fit connector between the first solenoid valve assembly and the body of the product manifold. the first, second, and third solenoid valve assemblies (144, 146,148) are secured to the body of the product manifold adjacent the first, second, and third control ports (138, 140, 142), respectively, by a corresponding snap fit connector (150, 152, 154); wherein the first solenoid valve assembly comprises a first housing having an opening facing the first control port, a control element being disposed within the first housing, the control element being shiftable between a first position and a second position relative to the first control port, and the product manifold comprises a biasing element and a control element guide having a bore and being disposed in the first housing, the control element being at least partially disposed within the bore of the control element guide, wherein the control element guide includes a first portion and a second portion, the first portion disposed adjacent the opening, the biasing element disposed between the first portion of the control element guide and the body of the product manifold to bias the snap fit connector between the first solenoid valve assembly and the body of the product manifold.