Thermally insulating article of warmth (e.g., apparel) includes thermally insulating flexible panels disposed and removably secured between outer shell fabric and inner lining fabric. Thermally insulating panels are inserted through an opening having a closure and are retained in position by detachable fasteners. Panels are removed to change them with panels having different thermal values or properties to adapt to different climatic conditions or to wash the article without the insulation. By removing the insulation panels article is less bulky to wash and dry and takes less time for washing and drying while preventing damage to the insulation, particularly if constructed of insulating material which absorbs humidity and has a tendency to form clumps when subjected to impact and stretching forces by the action of a washing and drying machine. Inner liner may also be detachable and formed as a pouch for removable securement of the thermally insulating flexible panels.