Angular 2: Cannot find name 'Subscription'

When trying to set the type of an attribute I get the error Cannot find name 'Subscription'. From which package do I import it from?

import { Component, OnDestroy, OnInit } from '@angular/core';
import { ActivatedRoute, Router } from '@angular/router';

// I'm missing an import here. Just don't know which package to load from.

@Component({
  moduleId: module.id,
  selector: 'my-component',
  templateUrl: 'my.component.html',
  styleUrls: ['my.component.css']
})
export class MyComponent implements OnInit, OnDestroy {

  private sub: any;

  constructor(private route: ActivatedRoute,
    private router: Router) {}

  ngOnInit() {
    this.sub = this.route.params.subscribe(params => {
       let id = +params['id']; // (+) converts string 'id' to a number
     });
  }

  ngOnDestroy() {
    this.sub.unsubscribe();
  }

}

Edit: Provide a more detailed code example.