With the Army transitioning to a single combat uniform, base layers are changing as well. There are already plenty of Operational Camouflage Pattern (OCP) uniforms being worn in the field and various positions throughout the Army and Air Force as the switch started back in 2018. Both branches are transitioning to the OCP; with the mandatory possession date of October 1, 2019, for the Army. The Operational Camouflage Pattern is slightly darker than previous patterns, which calls for a better complimentary shirt that is darker as well. For the Army, base layer shirts will have to be either Sand or Tan 499. To get ready for this change, here are four things you should know about Tan 499.