Kirkland is a master brand for the large warehouse chain Costco. They contract products from other manufacturers for an incredibly wide range of products — including various Whiskeys. These include a Canadian, Blended malt, and single malt Whisky (along with Tequilas, Gins, Vodkas, and more).
Their premium small batch Bourbon is made at Jim Beam. Kirkland Bourbon is not as smooth as Jim Beam, but it is aged seven years and is bottled at more than 51% ABV.