The Shipper's Letter of Instruction (SLI) helps exporters provide agents and forwarders comprehensive instructions. This letter provides vital shipping, commodities handling, and customs information. on guarantee seamless and effective shipping, we'll explain the shipper's letter of instruction and give a practical guidance on completing it. SIAM Shipping, an international transportation specialist, offers customized sourcing, shipping, and 3PL services. We excel in rail, ocean, air, and road shipping and prioritize efficiency and client satisfaction.