Magic Arch Foil Balloons are the easy way to make perfect arches using helium or air.
Small Magic Arch are 16"DiameterX 3.875"H in diameter Uses air only
Large Magic Arch balloons are 29.5"Diameter x 7.8"Diameter. When filled with helium you can make a floating arch.
If Filled with air they can be used with ACKIT2 found on this site under arch kits.