O.P.M.S Silver is known to be very different strain than others, its stronger and tends to have a stronger effect. It’s because it entails a mixture of plain leaf and a certain amount of extract.
Mitragyna Javanica grows in similar areas and is called Kra-Thum-Na. Mitragyna Javanica is another closely related species to both Mitragyna Hirsuta and Mitragyna Speciosa. The difference is in how the leaves have their chemical composition. Mitragyna Javanica does not have any Mitragynine in it. What researches has found is another compound called Mitrajavine. The alkaloid itself look like the one of Mitragyna Speciosa, Kratom but it is quite different in how it works and what effects it has.