Even before the F4F Wildcat had been purchased by U.S. Navy, the French Navy and the Royal Navy Fleet Air Arm (FAA) had ordered the Wildcat, with their own configurations, via the Anglo-French Purchasing Board. The F4F Wildcat (known in British service at first as the Martlet) was taken on by the FAA as an interim replacement for the Fairey Fulmar. In contrast to the USN F4F-3, the British Martlet Mk II was fitted with armor and self-sealing fuel tanks. The Mk II also had a larger tailwheel. For carrier operations, the "sting" tail hook and attachment point for the American single-point catapult launch system were considered important advantages. Nevertheless, the Martlets were modified to have British-style catapult spools.