Expansion shell: 1.size:m20,m22,m27,15/17. 2.process:cast steel/forged. 3.2-leaf or 3-leaf expansion shell. Expansion shell:. 1.size:m20,m22,m27,15/17. 2.process:cast steel/forged. 3.2-leaf or 3-leaf are both available. 4.expansion shell include expansion shell anchor head, thread bar, anchor plate and nut. 5.expansion shell was casting and machined. Expansion shell is an important part of expansion shell anchor bolt. expansion shell can provide prestressing to rock. It is veru convenient and easy to install. It is suited temporary support and permanent support. It maches with domed plate, nut and domed washer. And they are suited for use in single or twin grout tube installation due to the minimal rotation the bar undergoes the setting process.