From the brand Product Description Mid/End Caps: Slat Caps are made of high density polyethylene for high durability. Attach the wooden bars to the bottom of the bed Actual dimensions: 55mm wide x 10mm high (internal dimensions). Contents: 20 sheets For spring wood slats of 53, 5mm to 54.5mm wide. Suitable for wooden boards with a thickness of 8mm to 9mm < p>These plastic caps are ideal replacement parts for: metal beds, leather beds, wooden beds, sofa beds, bunk beds and more. Product details may vary slightly due to different production batches. If you mind the difference, please purchase cautiously.