Horizon Capital, the U.S. private-equity firm specializing in Ukraine, is investing $10 million in Ajax Systems, a Kyiv-based producer of wireless security systems.

Horizon Capital, the U.S. private-equity firm specializing in Ukraine, is investing $10 million in Ajax Systems, a Kyiv-based producer of wireless security systems. A competitor to Amazon’s Ring, another Kyiv-based security system designer, Ajax makes sensors that detect intruders, fire, and flooding and remote controls for household appliances, locks, and lighting. Founded in 2011, Ajax employs 500 people in Ukraine and largely sells to the European Union.