This Set of (4) AGC 4 Amp Fuses are perfectly suited for use with the Collins 516F-2 power supply. Many AGC-4 fuses and most all other standard AGC automotive type fuses are not 1.25 inch long as is required in a 516F-2 Fuse holder. The new AGC Glass Fuses are only 30 MM long, or about 1.181 inches. This makes them about 3/32 too short! They will not make contact correctly in the fuse holder and the power supply will not power up. My fuse measures 1 1/4 inch long and 1/4 inch in diameter as required for the Collins 516F-2 Power supply. These Cooper Bussmann fuses are not only of the highest quality but are both UL listed, and CSA compliant. The import fuses do not have this distinction and are not made with the same standards as the Cooper Bussmann, American Made fuses. It is very hard to find AGC 4 amp fuses at a good price as it is, and even if you do the new ones that are available, may not fit! Why put a cheap import, Non UL approved fuse in your fine Collins 516F-2 Power supply when you can use this fine product made in the USA? I have a limited supply and quantity of this product!