The Dornier Do.17 Z-10, was one of the last versions of Do.17. It was modified from a bomber to a night-fighter, because the Germans needed a night-fighter with a longer range. Among the improvements made, the Z-10 had a custom-built nose containing four 7.92mm MG 17s and two 20mm MG FF cannons, and the addition of heavy steel plates bolted to the nose bulkhead as extra armor, to protect the crew against frontal fire. The Z-10 contained an IR searchlight for the Spanner infrared detection system, but it proved to be a failure in practice; a single airplane was equipped with and tested the Lichtenstein radar system.