Ionic 2 select remove ok button and on tap over option value straight away

For some reason the popover interface isn't working for me:

	<ion-select interface="popover" [(ngModel)]="selectedPeriodId" (ionChange)="onPeriodChange()">
		<ion-option *ngFor="let period of periods" [value]="period.id">{{period.name}}</ion-option>
	</ion-select>