Gauge Adapter $8.99 The ideal way to install a fuel pressure gauge (such as our 100195) is with an Earl's pressure gauge adapter. Our selection includes sizes to accommodate all popular fuel line sizes.   larger image       Choose Size -6 Male To -6 Male w/ (1/8in) .125 NPT in. Hex Gauge Adapter $9.99 & $10.99 The ideal way to install a fuel pressure gauge (such as our 100195) is with an Earl's pressure gauge adapter. Our selection includes sizes to accommodate all popular fuel line sizes. larger image   Choose Size -6 Male To (1/4in) .25 w/ (1/8in).125 NPT in. Hex-6 Male To (3/8in) .375 NPT w/ (1/8in) .125 NPT in. Hex-8 Male To .25 NPT w/(1/8in).125 NPT in. Hex Gauge Adapter $14.99 & $19.99 The ideal way to install a fuel pressure gauge (such as our 100195) is with an Earl's pressure gauge adapter. Our selection includes sizes to accommodate all popular fuel line sizes. larger image   Choose Size -6 Male To -6 Female w/(1/8in).125 NPT in. Hex-8 Male To -8 Female w/(1/8in).125 NPT in. Hex-4 M to -4