Ricoh acquired Hitachi's print head technology research and development department, Hitachi had two good print head, HITACHI 256 I and HITACHI 256 II. VUTEK5300 and VUTEK3300, the two machines each with 16 HITACHI 256 I print heads, HITACHI 256 II print head is mainly used in HP Scitex: Idanit, Pressjet machines, HP Scitex Pressjet and HP tuberjet8300 with 150 HITACHI 256 II print head , Now no one has broken the record . I remember Taiwei promote Hitachi's print head in 2002, but until now fewer manufacturers use Ricoh print head on the market. 

Gen4 series  gray print head  384 nozzles are mainly three models:
Gen4 / 7pl   Dot frequency: 30KHZ
Gen4 / 14pl  Dot frequency: 30KHZ
Gen4 / 21pl  Dot frequency: 30KHZ

Gen3 E3 Series: 192 nozzles are mainly three models
Gen3 E3 / 15pl
Gen3 E3 / 30pl
Gen3 E3 / 45pl

Gen3 E1 Series: 92 nozzles Dot frequency: 30KHZ (once used by Tewei Teckpro H3200, H5000, Teckjet H2500 machines)
Gen3 E1 / 30pl
Gen3 E1 / 65pl