Modular devices, assemblies, and methods for coupling one or more fixation elements, such as bone fasteners and/or elongate rods. The device includes at least one coupling element having a body portion for receiving a bone fastener and an extension portion extending transversely from the body portion. A locking assembly is received in the coupling element and includes a locking member, a clamp portion, and a ring portion, wherein the locking member is configured to contact an upper portion of the clamp portion and the ring portion is configured to at least partially surround a lower portion of the clamp portion. When unlocked, the bone fastener is moveable within the clamp portion to allow for polyaxial movement of bone fastener relative to the coupling element, and when locked, the bone fastener is fixed relative to the coupling element.
