Mercury - Power Trim Sender - Fits SmartCraft Compatible Engines - 891777A01Mercury Power Trim Sender Starboard Side Digital Trim Feedback 891777A01 Overview A trim sender might be small, but when it does its job right, the whole boat feels more predictable. The Mercury Power Trim Sender (891777A01) is the starboard mounted sensor trusted on SmartCraft equipped engines to keep your digital trim readings steady and honest. Its the kind of part boaters rely on without thinking about ituntil the day the gauge stops moving and