The hilmor Fin Comb 16 & 17 and or the 18 & 20 are used as the final straightening process with the SHAECO® Straightening Tool.You are purchasing 2 (two) combs.hilmor Fin Combs 16 & 17, 18 & 20 FPI$20.00PriceExcluding Sales Tax | FREE SHIPPING $100+ Quantity*Add to CartSHIPPING INFODomestic Shipping to Lower 48 is Free for orders over $100.00. All others must fill out the Price Quote Form.