This is a very nice vintage Brooks Bros rain trench coat made in USA with imported material.  It appears to be treated poplin but no fabric tag found.

• Brooks Bros - Made USA imported fabrics
  
• Classic Styling with very nice detail - faux tortoise buttons with several spares - leather covered buckles cuffs and belt - 7 rows stitching under collar for shape - back pleat at hem - front slash pockets large enough for gloves etc. - sleeves lined but coat body is not lined so good warmer temp rainy weather - travels well - weight before packing 2#
  
• Size Marked 46 Reg - Back Length collar seam to hem 48" - Raglan Oversleeve collar to cuff 30 1/2" - Chest 56" and at belt line.
  
• Condition:  Vintage pre owned in very good condition Intact, clean, appears well cared for not used much