[Source] Kylo Ren's lightsaber was a crossguard lightsaber constructed by Kylo Ren, an agent of the First Order, sometime before or during 34 ABY. The lightsaber, based on an ancient design dating back to the Great Scourge of Malachor, contained a cracked Kyber crystal, requiring it to have lateral vents on either side of the handle in order to divert the extra heat generated by the crystal.