Abstract: Balloons and related components and manufacturing methods. Various embodiments provide balloons which define elastomeric balloon bodies and necks. The balloon bodies define body thicknesses and filled and unfilled internal volumes. Tension in the balloon bodies gives rise to internal pressures when the balloons are filled. The necks couple with the bodies and define neck thickness which differ from the body thicknesses. Various embodiments provide check valve for use with the balloons and/or various liquids. These check valves can comprise a ball that further comprises a generally spherical substrate of fine particles of a biodegradable material and a coating on the substrate. The coating can be made of another biodegradable material.