Reusable nut, replaceable ferrule For 1/32", 1/16", and 1/8" tubingSuitable for pressures to 280 bar (4000 psi)Fingertight nuts have a knurled surface designed to allow sufficient sealing force to be applied to the ferrule without wrenches. Hex style nuts allow wrench tightening; however, since they are polymeric, they can break, and are recommended for use only when space is limited and fingers will not fit.