Among the items was Hawking’s motorized wheelchair, used in the 1980s and 1990s. While the chair was expected to sell somewhere between £10,000 and £15,000, the ultimate price was nearly £300,000 (almost $392,000). The proceeds from the wheelchair will go to the Stephen Hawking Foundation and the Motor Neurone Disease Association, The Guardian reports.

Other Hawking items up for auction included signed books, manuscripts, a bomber jacket, and a copy of the Simpson’s script in which Hawking made his final cartoon appearance. A collection of Hawking’s medals and awards fetched nearly £300,000 ($392,000) more—again well above the expected price.

The most expensive item in Hawking’s collection was a copy of his Ph.D. dissertation on the expansion of the universe. The 1965 manuscript—one of five known copies—sold for nearly £585,000 (almost $764,000). It was expected to go for £100,000 to £150,000.

Hawking’s items were sold by Christie’s, a British auction house, as part of “On the Shoulders of Giants.” The full collection also included manuscripts by Isaac Newton, Charles Darwin, and Albert Einstein. Hawking’s dissertation was the single most expensive item.

According to The Guardian, Hawking’s children plan to donate the rest of their father’s estate to the nation as part of the “acceptance in lieu” scheme, which allows one to transfer objects of artistic or historical value into public ownership to pay down inheritance tax.

Hawking passed away at the age of 76 in March of this year after living with a severe motor neuron disease—amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease—since his days as a graduate student. He was well-known for his work on black holes and the laws of the universe.