GOD'S WORD® Translation
The power of these horses is in their mouths and their tails. (Their tails have heads like snakes which they use to hurt people.)

American Standard Version
For the power of the horses is in their mouth, and in their tails: for their tails are like unto serpents, and have heads; and with them they hurt.

Berean Study Bible
For the power of the horses was in their mouths and in their tails; indeed, their tails were like snakes, having heads with which to inflict harm.

Douay-Rheims Bible
For the power of the horses is in their mouths, and in their tails. For, their tails are like to serpents, and have heads: and with them they hurt.

English Revised Version
For the power of the horses is in their mouth, and in their tails: for their tails are like unto serpents, and have heads; and with them they do hurt.

King James Bible
For their power is in their mouth, and in their tails: for their tails were like unto serpents, and had heads, and with them they do hurt.

World English Bible
For the power of the horses is in their mouths, and in their tails. For their tails are like serpents, and have heads, and with them they harm.

Young's Literal Translation
for their authorities are in their mouth, and in their tails, for their tails are like serpents, having heads, and with them they do injure;

Revelation 9:19 Additional Translations ...