title: Selecting correct boxes in *ngFor
body: <p>I am working on a angular application. I am facing some issues in *ngFor. my code is as follows</p>
  <p><a href="https://stackblitz.com/edit/ngx-slider-simple-slider-example-xfkvcj?file=src%2Fapp%2Fapp.component.html" rel="nofollow noreferrer">https://stackblitz.com/edit/ngx-slider-simple-slider-example-xfkvcj?file=src%2Fapp%2Fapp.component.html</a></p>
  <p>The problem I am facing is if I click on second box  then with it fourth box is getting clicked automatically and same is the case with first value. I want if I click on second box then only second box is clicked and same follows with other boxes. How can I do that?</p>