The W66 had a yield of 2 kilotonnes of TNT (8.4 TJ) and was an enhanced radiation ("neutron") weapon. The W66 was 18 inches (46 cm) in diameter and 35 inches (89 cm) long, with a weight of approximately 150 pounds (68 kg).
The W66 was based on the Arrow warhead design and by December 1966 had undergone six nuclear tests.
- L C Harrison; W R Preeg; B B Rogers; JL Stokes; J R Lilley; M Henderson (July 1977). Output for the Sprint Warhead (Report). Los Alamos Scientific Laboratory. p. 1. Archived from the original on 2022-06-20.
- Minutes of National Security Council Meeting (Report). Parity, Safeguard, and the SS–9 Controversy. Washington DC. 1969-05-05. p. 54. Archived from the original on 2022-10-08. Retrieved 2022-06-25.
- Carey Sublette. "List of All U.S. Nuclear Weapons". Nuclear Weapon Archive. Retrieved 2022-06-24.
- Robert McNamara (1966-12-02). Production and Deployment of the Nike-X (PDF) (Report). Secretary of Defense McNamara Memorandum for the President. p. 23. Archived (PDF) from the original on 2022-01-21. Retrieved 2022-06-24.