Four kinds of horses (Zechariah 6: 1-3)
And I turned, and lifted up mine eyes, and looked, and, behold, there came four chariots out from between two mountains; and the mountains were mountains of brass.
2 In the first chariot were red horses; and in the second chariot black horses;
3 And in the third chariot white horses; and in the fourth chariot grisled and bay horses.
Zechariah 6:1-3 - King James
⚪ Symbolize four companies of saved ones.
(The four kinds of horses of Zech. 6:1-8 seem to refer to four companies of saved ones. Red, the Ancient Worthies; black, the Little Flock; white, the Great Company; bay, the world of mankind.)
Source : 🇺🇸 1917 - Studies in the Scriptures, Vol 7, The finished mystery, page 164 + Cover
⚫ Do not symbolize anything
[...] there were four chariots coming forth from between two mountains, and the mountains were copper mountains. In the first chariot were red horses; and in the second chariot, black horses. And in the third chariot there were white horses; and in the fourth chariot, horses speckled, parti-colored."- Zechariah 6:1-3.
We need not make guesses as to what the differentiating colors of the horses mean. The colors of the horses served to distinguish the chariots pulled by each color group. How many horses were hitched to each chariot, Zechariah does not tell us.
Source : 🇺🇸 1972 - Paradise restored to mankind by theocracy, page 222, page 223 + Cover
Note : The chariots symbolize the "four spirits of the heavens" (page 225)