There are four full-sized casts of this sculpture: Abingdon Street Gardens in the City of Westminster, the Bloedel Floral Conservatory in Queen Elizabeth Park in Vancouver, and the Rose Garden of the Rockefeller family house at Kykuit at Tarrytown, New York. The forth was retained by the artist, but later donated to to the Henry Moore Foundation in 1977, and it is displayed at Perry Green, Hertfordshire.
Many people call this sculpture "Knife Edge Two Piece" or "Knife Edge (Two Piece)", but Moore called it "Two Piece Knife Edge".
Also seen here at VG:
http://virtualglobetrotting.com/map/knife-edge-two-piece-by-henry-moore/