The 24-story Carlyle condominium building will open next summer, and the 78 units have de rigueur designer features such as Miele appliances and price tags that start at $2.9 million.

But the Westwood tower at 10776 Wilshire Blvd. has one more exclusive feature: 20 “nanny condos.”

The second-floor nanny units are tiny, ranging from 294 square feet to 504 square feet, but still feature some nice touches, such as Kohler fixtures and Poggenpohl cabinetry. As a result, the units start at $400,000 and carry a per-square-foot price that averages close to $1,500 about the same as the regular units.

The Carlyle was designed to attract wealthy empty-nesters looking to downsize, but not so much that they would have to make do without their butlers.

New York-based developer Elad Properties claims interest has been high, with two nanny and 10 regular units already sold.

“If somebody has a staff, it is a no-brainer for them,” said Erik Schneider, director of sales for the property.

But Stephen Shapiro, chairman of Westside Estate Agency, a residential brokerage specializing in luxury properties, said Elad is trying to sell nanny units in an incredibly difficult market.

“It sounds like a lot of money to me,” said Shapiro. “It is more difficult to move everything, let alone the nanny units.”