I am using *ngFor and it has me perplexed. I am trying to use UIkit but it would be applicable to Bootstrap also.
Just use index that directive provides
like
*ngFor="let device of devices ; let i = index"
then in the html just check with *ngIf and add your block
like
Probaly you need this approach Ng-repeat-start in angular2 - aka repeat multiple elements using NgFor
(in AngularJS 1.x it was pair of directives ng-repeat-start ng-repeat-end, now it's another approach for the same)