4" NPT Female x 3.5" NPSH Male Adapter Aluminum FM6060F The difference is just that

The difference is just that

The Gel provides a fire-stopping “barricade” for the homeowner to “prepare

We recommend using this hose for anything that requires linen materials

Threaded Size (Inside Diameter): 2" Male NPT (National Pipe Tapered)

4" NPT Female x 3.5" NPSH Male Adapter Aluminum FM6060F The difference is just thatSpecifications Female Side 1 4 NPT Female (National Pipe Tapered) Male Side 2 3. 5 NPSH Male (National Pipe Straight Hose) Working Pressure 300PSI Max Test Pressure 1000PSI Max Material T 6061 Aluminum (Aircraft Grade) Finishing Anodized (99. 9% Lead Free) NFPA Standards 1963, 4. 12, 5. 1 5. 6. 4 (Corrosion Resistance) Military Standards MIL A 8625 Type III, Class 1 Industrial Standards International ASTM B221 UL Labs Standards 236 8. 1 Through 8. 2