SERAPHIM - (singular "Seraph"), mentioned in Isaiah 6:1-7 - It means "the burning ones" because they are closest to God and they radiate Pure Light.
It is noted that there are four of them serve as the caretakers of God throne.
These Angels are the ones who constantly sing God's praise; they are also commissioned to regulate the heavens.
The Seraphim have six wings; two covering their faces, two covering their genitals, and two with which they fly.
Scholars say that they have been described as being so bright in that light emanates from them, nothing, including other angelic beings,can look upon them.
Two Seraphim are named Seraphiel and Metatron, according to some books. Lucifer is said to have been one of the Seraphim who had outshone all the others until he became the head of the fallen Angels. It is also theorized that Jesus is above these Seraphim because he sits on the right hand side of Gods throne.
1st Sphere - Seraphim -Cherubim-and Thrones
2nd Sphere - Dominions -Virtues-Powers-
3rd Sphere - Principalities -ArchAngels- Angels-