Comparison : Item # W121-2, 1/8" Thread Size Compliant Yellow Brass Hex Head Plug
Item # W121-4, 1/4" Thread Size Compliant Yellow Brass Hex Head Plug
Item # W121-6, 3/8" Thread Size Compliant Yellow Brass Hex Head Plug
Item # W121-8, 1/2" Thread Size Compliant Yellow Brass Hex Head Plug
Item # W121-12, 3/4" Thread Size Compliant Yellow Brass Hex Head Plug