Solid Viton rubber, with metal jacket and choker spring. Stem diameter: 6mm, valve guide diameter: 0,385"; over all length of seal: 0,371"; outside diameter of seal: 0,480". Kibblewhite Precision Machining custom valve stem seals are a quality product and suitable for any and all custom application. Note: Below mentioned valve stem diameters are for reference only. - 36-84 B.T. = 3/8" (.3750") - 57-83 XL intake = 0.3090" - 57-83 XL exhaust = 0.3384" - 84-04 B.T.; 86-03 XL = 5/16" (.311") - 05-16 TCA/B; 04-22 XL; 08-12 XR = 7mm (.2760") - 02-17 V-Rod = 6mm (0.2345") - 17-24 M8 = 6mm (0.2345")