STRUCTURES' ASSEMBLY INSTRUCTIONS o Swing out cross arms to 90 degrees. Place the rivets of the cross arms into the key hole for your mattress size (see Figure 1), then slide the lock into place, Attach the center support bar to the cross arms for Queen o Install rollers or glides as shown in Figures 3 and 4. and Full configurations. The Twin configuration doss not Place support legs under holes that align on center of require center support. cross arms, Screw in as Shawn in Figure 5.