The MkVII was a British design  but also built in the US. The US D7  design was very similar. These were L.A. (Low Altitude) types typically flown at around 5,000 feet in a roughly 5° nose-up attitude.

More than 30,000 barrage balloons of various types were built by the US and Britain during WW2 and were effective against low level and dive bombing attacks.  They also had a degree of success against V1 “Doodlebug” flying bomb attacks against London.

H.A. (High Altitude,  12 to 15,000 feet) types lost favor early in the war owing to the inherent handling difficulties. V.L.A. (Very Low Altitude types, around 1,000 feet) were increasingly used as the Allies went on the offensive, most noticeably during the D-Day landings and invasion of Italy.

MkVII:     64ft long, 25.25 ft diameter, 40.5 ft high