This is the Trumpeter 02313 kit in 1/35 scale, of the ‘German 17 cm Kanone 18’.
The 17 cm Kanone 18 in Mörserlafette was a German heavy gun used in the Second World War. It was intended to be employed at the Corps level in order to provide very long-range counterbattery support. It filled the same basic role as the 21 cm Mörser 18, as well as sharing its carriage, and replaced it entirely after 1942.
Although it was technically an excellent weapon, it was expensive, difficult to maneuver, very slow to set up and tear down; many were lost when their crew had either to abandon them or to risk capture by advancing allied troops.
Where I got it