260102, 280105 - Plain single line circles. Inscriptions in Greek characters, including the following: Α α Β β Γ γ Δ δ Ε ε Ζ ζ Η η Θ θ Ι ι Κ κ Λ λ Μ μ Ν ν Ξ ξ Ο ο Π π Ρ ρ ς Σ σ Τ τ Υ υ Φ φ Χ χ Ψ ψ Ω ω.