This item is similar to the Belt of Giant Strength, but it's weaker, and it doesn't require attunement. It's a fair and viable item that does its job, and doesn't present any balance issues or serious concerns. A good choice for your monks or rogues, who don't focus on Strength but could certainly use it if they had more of it. Not so much for your fighters or barbarians, who are likely to have a greater score than 15 at the point where magic items are being handed out.

That’s precisely what I designed it for.

Good to take as an Armorer or Battle Smith Artificer before you can get a Belt of Giant Strength or Gauntlets of Ogre Power.  Fits the theme of wearing a metal mechsuit that gives you mechanical strength.  

Quote from CoolerKoolaid >>

This item is similar to the Belt of Giant Strength, but it's weaker, and it doesn't require attunement. It's a fair and viable item that does its job, and doesn't present any balance issues or serious concerns. A good choice for your monks or rogues, who don't focus on Strength but could certainly use it if they had more of it. Not so much for your fighters or barbarians, who are likely to have a greater score than 15 at the point where magic items are being handed out.

 Also useful for Clerics since they get proficiency in heavy armor but may or may not have the Strength requirement to wear full plate or splint.