That means Cypress (now Infineon) has issued a last-time-buy notice for this QDR II SRAM. If your design depends on this exact density and speed grade, the window to secure final production quantities is open now. Once the LTB window closes, the only channel will be surplus and broker stock — with the price and availability risk that entails.
This is a QDR II (Quad Data Rate) synchronous SRAM running at a 300 MHz clock. The QDR II architecture delivers four data words per clock cycle — two on the read port and two on the write port — giving an effective data rate that keeps a high-performance FPGA or network processor fed without dead cycles. The 18 Mbit density is organized as 1M x 18, so it fits designs that need a deep, wide word for look-up tables, packet buffers, or cache.