Idex Flangeless Nuts: Compatible with 1/4-28, PEEK, For Use With: For 0.06 in. O.D. Tubing, Port Style: 0.25 to 28 flat bottom, Flangeless standard knurled head short nut, Quantity: 10/Pk., Certifications/Compliance: ROHS, Natural, Dimensions: 0.61 x 0.37 in. (1.54 x 9.4 cm)