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In page M109 howitzer:

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  •  Switzerland: Purchased M109A1B and introduced them in 3 batches: 120 Pz Hb 74 from 1974 to 1978, 207 Pz Hb 79 from 1981 to 1983, and 108 Pz Hb 88 from 1991 to 1992. Also upgraded 146 M109 to M109A1B standard from 1977 to 1979.[1] The total number of received vehicles is 581[citation needed]