13-1. Conditions of Performance. The Caplans con- tract with Faithful Construction, Inc., to build a house for them for $360,000. The specifications state all plumbing bowls and fixtures ... to be Crane brand. The Caplans leave on vacation, and during their absence, Faithful is unable to buy and install Crane plumbing fixtures. Instead, Faithful installs Kohler brand fixtures, an equivalent in the industry. On completion of the building contract, the Caplans inspect the work, discover the substitution, and refuse to accept the house, claiming Faithful has breached the conditions set forth in the specifications. Discuss fully the Caplans' claim. (See Performance and Discharge.)