A lot of guys “flash” brick-mold doors and windows by running a bead of caulk down the back. Straight Flash VF (for “versatile flange”) is configured to serve as a real flashing flange. This self-adhered Tyvek flashing membrane has perforated release paper on both sides; you peel off half of one side, stick it to the back of the brick mold, peel off the same half of the opposite side, then put the door or window in the opening. A 6-inch by 125-foot roll costs $160.
Dupont, 800/448-9835, dupont.com.