Detail & Specs This configuration is not available. Make another selection. TNS1/4-20 - Plain Steel Nut Sert - 1/4-20" American Steel Nut-Sert Insert Steel Poly-Nut. 3/8" Hole Size Grip range: .030" to .165" Metric Nuts, Marson, Bel-Metric, TNS1/4-20 - Plain Steel Nut Sert