The KV-1E Model 1940 was a heavily armored version of the KV-1 with a 76.2 mm F-32 gun. To better protect the KV-1 bolted on armor was added. In July 1941 M1940 KV-1s had appliquéd armor panels applied and were re- designated KV-1E Model 1940 [E stands for "s Ekranami" – literally KV with screens also referred to as appliquéd armor]. The added armor worked but overall it was more of a hindrance than help. This modification along with a few others brought the weight from 43 tonnes to 50 tonnes and added so much weight that there were frequent drive train breakdowns. But most losses came from Ju-87s, infantry with flamethrowers and anti tank guns like the Flak 36.