details about product: Button-Down Collar Non-Iron Stretch Poplin Mini Gingham Check Shirt - Ocean Blue

The issue here is with the difference between casual shirts (ordered here) and formal/business shirts, which were ordered previously and you are basing your sizing needs on. Formal shirts allow for multiple sleeve length options - and based on your last order, you need a longer than average sleeve length - 36" with a 15.5" collar, which is 2" longer than "standard" for the size. The casual shirts, I'm afraid, only offer this standard length - to receive a longer sleeve length, it requires a larger size to be purchased. To receive a casual shirt with a 36" sleeve length, it would require purchasing a size XL casual shirt. I hope that provides some clarity on the sizing and is helpful if/when next considering ordering casual shirts. Alternatively, you may need to stick to the formal shirts, to ensure you can purchase a long-enough sleeve.