Boa The BOA lacing system allows for precise and effortless fit adjustments. The BOA evenly distributes pressure and allows for micro-adjustments to the lacing. It’s simple; push in the knob and twist clockwise to tighten, pull out the knob and push the tongue forward to loosen. Echo Liner Echo Liner is built of lightweight foam and has a front lacing system with reinforced lace locks, so you can get your foot in the liner more quickly and with less fuss. The Echo liner reduces bulk and eliminates heel lift, and the calf area is lined with soft, comfortable padding to help keep your calves from getting tenderized.