TennaTie
The TennaTie (JP: テナタイ Tena Tai) is an armor found in Chapter 3 of Deltarune that can be obtained only once as a gold prize from the ball machine in the Green Room. It can be equipped to any party member, and it gives +5 DF and -2 Magic. It is the only armor in the game that decreases the Magic stat; due to Kris being unable to benefit from Magic, it has no downside if equipped onto them.
Starting in Chapter 5, Malius can fuse the TennaTie with a FrayedBowtie to create the TrueTie.