Buy with Confidence: With Monoprice's Lifetime Warranty on all Cables, you can rest assured we stand behind our products and our customers. Null modems are used to connect two computers or other devices together to achieve file transfer. Null modem connectors are different from straight through connectors because the receive and transmit conductors are crossed. This is a miniature null modem with a male connector on one side and a female on the other. Monoprice continually strives to improve its product line to bring our customers the best products available