From the article:
Panzerkampfwagen IV Ausf H entered production in April of 1943 as the ninth variant of Panzerkampfwagen IV tank family. Designated Sd Kfz 161/2 it was produced between April 1943 and July 1944 when it was replaced by the Ausf J.
It was the most produced of all the Panzer IV variants with 2,774 tanks produced and another 30 hulls being used for early StuG IVs and 130 for Brummbärs. It was produced by Krupp-Gruson AG in Magdeburg, Vomag AG in Plauen and Nibelungenwerke AG in St. Valentin.
The Panzer IV H was basically a late model Ausf G with six-speed Zahnradfabrik ZF SSG76 transmission. Another modification to take place during production in June 1943 was to increase the front armour from 50mm with an additional 30mm plate, to a one-piece 80mm plate on the front hull and superstructure.
Additional modifications included the removal of side superstructure visor ports (June 1943), application of Zimmerit paste (September 1943), modifications to the suspension (September-November 1943), air filters, a new commander's cupola and anti-aircraft MG34 cupola mount (Fliegerbeschussgerat).
Panzer IV H models were almost universally fitted with armour side skirts (Schürzen, hull 5mm and turret 8mm) to give added protection against light anti-tank weapons and hollow charge weapons (HEAT). All Panzer IV H tanks were armed with 75mm KwK 40 L/48 gun and two MG 34 machine-guns (co-ax and hull mounted).
Like all Panzer IVs it had a crew of five: a commander, gunner, loader, radio operator and driver.
On 6 June 1944 (D-Day) the majority of Panzerkampfwagen IV tanks present in France were the Ausf H model