The Škoda 75 mm Model 1928 (75 mm M.28) was a mountain gunmanufactured by Škoda Works and exported to Yugoslavia. It was a modernized version of the Škoda 75 mm Model 15. The gun typically had a 75 mm barrel; however, it could be fitted with a 90 mm barrel. The Wehrmacht redesignated these guns as 7.5 cm GebK 28 (in Einheitslafette mit 9 cm GebH) or 7.5 cm GebK 285(j). The gun crew was protected by an armouredshield.
Chamberlain, Peter and Gander, Terry. Infantry, Mountain and Airborne Guns
Gander, Terry and Chamberlain, Peter. Weapons of the Third Reich: An Encyclopedic Survey of All Small Arms, Artillery and Special Weapons of the German Land Forces 1939-1945. New York: Doubleday, 1979 ISBN0-385-15090-3