Brief Announcement: Fast Dual Ring Queues Joseph Izraelevitz and Michael L. Scott In this paper, we introduce two new FIFO dual queues. Like all dual queues, they arrange for dequeue operations to block when the queue is empty, and to complete in the original order when data becomes available. Compared to alternatives in which dequeues on an empty queue return an error code and force the caller to retry, dual queues provide a valuable guarantee of fairness. Our algorithms, based on the LCRQ of Morrison and Afek, outperform existing dual queues -- notably the one in java.util.concurrent -- by a factor of four to six. For both of our algorithms, we present extensions that guarantee lock freedom, albeit at some cost in performance.