The Air Force has finished testing four versions of its new stain-resistant boot, to be worn with the new Airman Battle Uniform (ABU). The 200 airmen who took part in the test generally favored a prototype that offered a rubber heel and toe cap. They also expressed concerns that the boot was heavy, and should offer better breathability and traction. Until a suitable new boot is developed, the service likely will authorize airmen to wear black boots in certain work areas.