Seiko bullhead can be classified into 2 main type:
1.Black bullhead
 | Dial version : Seiko Chronograph Automatic Reference number : 6138-0040 Movement : automatic, Seiko Caliber 6138B Dial reference number : 6138-0060T Dial Indexes : Luminous Day wheel variations : English/Spanish, English/Kanji , English/Arabic Hours/Minute hand color : Black/White with luminous material Chronograph Hours/Minute hand Color : White Chronograph Sweep Second hand Color : Yellow Bazel : Black color, "TACHYMETER" in silver, Number in silver, Index in Silver Bracelet : Fishbone |
2.Brown bullhead
Seiko Brown Bullhead has 3 dial versions: Seiko Chronograph Automatic, Seiko Speed-Timer, and Seiko 5 Sports Speed-Timer.
 | Dial version : Seiko Chronograph Automatic Reference number : 6138-0049 Movement : automatic, Seiko Caliber 6138B Dial reference number : 6138-0060T Dial Indexes : Luminous Day wheel variations : English/Spanish Hours/Minute hand color : Black/White with luminous material Chronograph Hours/Minute hand Color : Black Chronograph Sweep Second hand Color : Yellow Bazel : Brown color, "TACHYMETER" in Gold, Number in silver, Indexes in Gold Bracelet : Fishbone |
Dial version : Seiko Speed-Timer Reference number : 6138-0040 Movement : automatic, Seiko Caliber 6138B Dial reference number : 6138-0071T Dial Indexes : Non-Luminous Day wheel variations : English/Kanji Hours/Minute hand color : Black/White without luminous material Chronograph Hours/Minute hand Color : Black Chronograph Sweep Second hand Color : Red Bazel : Brown color, "TACHYMETER" in Silver, Number in silver, Indexes in Silver Bracelet : Seiko Speed-Timer Bracelets |  |
 | Dial version : Seiko 5Sports Speed-Timer Reference number : 6138-0040 Movement : automatic, Seiko Caliber 6138B Dial reference number : 6138-0070T Dial Indexes : Non-Luminous Day wheel variations : English/Kanji Hours/Minute hand color : Black/White without luminous material Chronograph Hours/Minute hand Color : Black Chronograph Sweep Second hand Color : Red Bazel : Brown color, "TACHYMETER" in Gold, Number in silver, Index in Gold Bracelet : Seiko Speed-Timer Bracelets |
