TT points to the distinctive blood applications of the miluim ram (right ear, right thumb, right big toe) on Aharon and his sons.
ויקח משה מדמו ויתן על תנוך אזן אהרן הימנית ועל בהן ידו הימנית ועל בהן רגלו הימנית — וכן לבניו. דם המילואים ניתן על תנוך האוזן ועל בהן היד והרגל של אהרן ובניו.
“And Moshe took of its blood and put it upon the tip of Aharon’s right ear, and upon the thumb of his right hand, and upon the big toe of his right foot” — and likewise for his sons. The blood of the miluim ram is placed on the right ear-tip, right thumb, and right big toe of Aharon and of his sons.
Custom — distinctive blood rite of the miluim.
From the blood of the installation ram Moshe places blood on the right ear, right thumb, and right big toe of Aharon and of each of his sons.