Costco's Kirkland Signature golf balls have taken the golf world by storm since their introduction in fall 2016.
The first Kirkland Signature golf balls -- commonly called the K-Sig -- were originally sold at the absurdly low price of $30 for two dozen. The original four-piece ball, which is thought to potentially be the leftovers from an overrun of golf balls made for a major manufacturer, sold out several times online and at the rare Costco where they were available in person.
The first wave of golf balls were made by Nassau Golf Co. Ltd. of South Korea. The four-piece ball had a 360-dimple pattern and was a medium-to-high spin ball around the greens, according to the USGA's conforming ball list.
Then, in 2018, a new wave of Kirkland Signature balls hit the market. This time, there were two models of the golf ball, with similar pricing for two dozen balls at a time. There was a three-piece model and a four-piece model.
The three-piece model was dubbed the Performance Plus ball. It's a three-piece golf ball with a similar urethane cover to the four-piece ball. Costco described the product online as having a "low compression highly elastic rubber core." In other words, it was a softer golf ball.
The new four-piece ball that came out in 2018 wasn't the same as the original. Like the three-piece model, it had a 338-dimple pattern.
SM Global LLC, an American subsidiary of a Korean company that is the second manufacturing partner for Costco golf balls, produced these balls.
The rub on the original Kirkland Signature golf balls was the four-piece model didn't provide quality greenside spin. Then the recipes for the ball changed, and it became more difficult to approximate which ball the K-Sig three-piece and four-piece actually were. However, they appear to be a softer golf ball than the original, making it less ideal for players with faster swing speeds and potentially slower for all golfers. The potential for greenside spin depends on the materials in the golf ball itself, giving a softer cover a firmer next layer to build spin.
Now, the K-Sigs are back (and already sold out online) in fall 2019. It appears the latest release is still these second-generation models, meaning golfers shouldn't expect the same performance as the original.
Sept. 24 Update: After numerous reports of customers cutting the new balls' covers with relatively few swings and more reports of unreliability, Costco is refunding the full purchase price to customers with an emailed apology for the poor quality of the latest Kirkland Signature golf ball.