A very sturdy one-piece molded polypropylene rack. All four sides can be used interchangeable for 12mm through 25mm diameter tubes. Rack features a total of 88 spaces on its four sides. Shipping weight: 0.75 lbs.; Dimensions: 8 x 4 x 4-1/2 inches. Shipping Details Shipping Type: parcel Free Shipping: true Specifications Maximum Age: N/A Maximum Grade Level: N/A Grade Level: Grades 6-12 SUOM Description: Each Brand Name: United Scientific Description: Plastic Test Tube Rack