Why shell out a few hundred dollars for a fresh wedding cake when you can get some of Prince Charles and Princess Diana’s nuptial dessert for roughly the same price?

As The Washington Post reports, a piece of cake from their royal wedding in July 1981 is hitting the UK auction block next week, with an estimated price tag of £200 to £300 (about $300 to $400). Dominic Winter Auctioneers does “advise against eating it,” so if your main criterion for cake is edibility, it might not be worth the money.

It’s also not, strictly speaking, cake—but rather a thick slab of white icing decorated with “a sugared onlay of the Royal Coat-of-Arms colored in gold, red, blue, and silver, a small silver horseshoe and leaf spray adjacent,” and some other embellishments. The whole thing tips the scales at 28 ounces and measures approximately 8 inches by 7 inches.

As royal family aficionados may already know, Diana and Charles didn’t have just one wedding cake. The main offering was a 5-foot-tall, five-tier, 225-pound fruitcake created by the Royal Naval School of Cookery’s head baker. But there were about two dozen other wedding cakes baked and distributed among important people and places. The icing up for auction is believed to have come from one given to the staff at Clarence House, where Queen Elizabeth the Queen Mother (Queen Elizabeth II’s mother) lived. (It’s now the official residence of Prince Charles and Camilla, Duchess of Cornwall.) Moyra Smith, a Clarence House staff member, kept the icing wrapped in plastic for years, and her family sold it in 2008.

Along with the dessert, the winning bidder will receive two printed programs: one from Diana and Charles’s wedding ceremony at St. Paul’s Cathedral, and another from the official royal wedding breakfast held that day at Buckingham Palace. The live auction takes place on August 11, and you can find out how to bid online here.

[h/t The Washington Post]