Total length: 175 mm Expansion Tube length: 75 mm, diameter: Ø12 mm Support Rod length: 100 mm, diameter: Ø10 mm The Plank Support Bracket can support and fix all kinds of wall shelves, such as bookshelves, display stand, garage storage racks, decorative shelves, bathroom shelf, shoe shelving, etc. It can definitely satisfy your various DIY wall bracket designs. Installation Steps: 1. First measure the hole spacing and drill the hole in the wall, the depth of the hole should small than 75mm. 2. Insert the bracket support pin into the wall hole together with the expansion plug and the black screw cap at the end. 3. Tighten the support rod clockwise, and rotate it until the expansion plug in the wall expands to fully support the wall. 4. Then drill the hole of the corresponding size on the side of the board (consistent with the hole spacing of the wall). 5. Finally, insert the board to the plank support rods. Please Read The Following Tips: 1. You need to prepare a 11mm drill bit for drilling holes in the wall and another 10mm drill bit for drilling holes in the wood. 2. Remember to place the middle silver metal ring on one side of the expansion tube and embed into the wall. 3. Each board must have at least 2 invisible brackets and be kept in the same horizontal position.(the 2 pcs holder can bear about 11 lb/5 kg) Notice: It is best to drill a hole in a scrap wood to try the diameter of the hole to achieve the effect you want. Material:Plastic + Metal colour:Brown Package Contents: 24 x Concealed Floating Shelf Brackets