This manual introduces the Trenz Electronic GigaBee XC6SLX series of industrial-grade FPGA micromodules. These micromodules integrate a leading-edge Xilinx Spartan-6 LX FPGA, Gigabit Ethernet transceiver (physical layer), two independent banks of 16-bit-wide 128 MB DDR3 SDRAM, 8 MB SPI Flash memory for configuration and operation, and powerful switch-mode power supplies for all on-board voltages. A large number of configurable I/Os are provided via robust board- to-board (B2B) connectors. All this on a tiny footprint, smaller than half a credit card, at the most competitive price. Hardware and software development environment, as well as reference designs are available at: www.trenz-electronic.de.