That's pretty simple Joe, Delrin is just simply a better material in all respects, if the call was made exclusively for heavy duty field use. It's tougher, it's more stable, it drills much more precision and it is consistant. In short, it is everything that horn isn't, except charming for folk art or collector calls. Generally I use ivory, but this call is made to be tough as a shovel handle (because that's what it's made from). It's not for looks, but for performance and durability only. Some folks find that those qualities have a certain charm.