Here we have a better than OEM quality fork seal  kit to fit the following Montesa 4RT Trials Bikes fitted with 39mm Forks:
4rt 260 14-23
COTA 300RR 16-23 
These seals and dust covers offer Lower Stiction, Longer Life, Patented fork seal design features a balanced 2 lip design on the oil (pressure) side that evenly distributes the pressure reducing operating temperature, wear and friction. A 3rd lip on the air side acts as an additional wiper to prevent dirt from contaminating the oil. A custom elastomer reduces stiction (friction) from 1/3 to ½ less than the OEM seals for smoother fork action.