The variable filter dial.
Stears
J G
JG
Mayo Clinic/Mayo Foundation, Rochester, MN
Gray
J G
JG
Frank
E D
ED
D000535:Aluminum; D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D011835:Radiation Protection; D013679:Technology, Radiologic / Q000295:instrumentation* / Q000592:standards
D000535:Aluminum