Review on 🔧 High-Quality Aluminum Thread Allen Socket Plugs: Durable and Efficient Solutions by Brett Slater

This is just the right size for NPT plugs. Some reviewers seem to be misinformed about how the NPT diameter is measured. Based on the bad reviews I thought the plugs might be mislabeled but after receiving them they were fine, some high temp Permatex thread sealant and it worked great. : A 1/4 NPT male has an outside diameter of about 3/8, which is perfectly correct. Installed to cover the regulator hole in my aluminum v-twin engine block instead of using a big chunky bolt. A bit pricey and took a while to arrive but they are high quality and I will be ordering more.