Tensioner Slat Kits from Furnacc. Easily strengthen the existing flexible slats on your slat bed. Each kit consists of 5 narrow flexible slats and 10 or 20 plastic tension adjusters. This is sufficient to fit to 5 rows on one side of one bed. Widths available are 53mm and 38mm for all bed sizes. Click on 'Pricing' tab (below) for prices.