Berkley IronSilkTM, 12lb | 5.4kg, 300yd | 274m Monofilament - 12lb | 5.4kg - 300yd | 274m Tough As Iron, Smooth As Silk Tough As Iron -- Outlasts Other "Tough"Lines 2 To 1. Even Over ZebraMussels And Oyster Beds. Smooth As Silk -- Extremely Smooth Surface ForLong And Smooth Casts Ultra-Low Memory -- Virtually No Coils. HandlesGreat On Spinning And Casting Reels. Sensitivity With Shock Strength --A Breakthrough Combination Of Properties