To ensure you have the perfect fit, you should be able to comfortably slide a finger between the collar and your neck

Free Shipping On all orders over $100.00 MSC8744EPZ Puracol Plus AG+ Collagen Wound Dressings with Silver (10/BX) Medline $511.85 SKU: MSC8744EPZ MSC8744EPZ Puracol Plus AG+ Collagen Wound Dressings with Silver (10/BX) Puracol Plus AG+ Collagen Wound Dressing with Silver 4.25" x 4.25" Details: 10 per box Dressing Dimensions: 4.25" x 4.25" Puracol Plus AG+ collagen wound dressings with silver help jump-start stalled or chronic wounds 1,2,3 when antimicrobial properties of silver are desired and help promote natural healing High-quality 100% collagen powder maintains a high degree of nativity 4,5 High gel integrity 6 helps the dressings stay in good contact with the wound bed over time Indications: pressure, venous, diabetic ulcers, partial and full-thickness wounds, ulcers caused by mixed vascular etiologies, first- and second-degree burns, donor sites and other surface wounds, abrasions, traumatic wounds healing by secondary intention, and dehisced surgical wounds Contraindications: active vasculitis or patients with known sensitivity to collagen or silver

Going without the traditional, sharp shirt collar means it's suited for casual occasions and to be honest more comfortable, too
XL fits perfect if your a size 18