These have a zinc electroplated mild steel strap cast in to the anode. The strap is generous in length to cover even the widest stud pitch. Trick. It may be a good idea to buy 2 anodes. You fi t one but keep the other in the shed. Drill both out. When you discover to your horror that your anode has dissolved out, you have an immediate replacement, predrilled.

Don't forget to buy another spare!

Dimensions: 160(L) x 80(W) x 23(D)mm, 290mm strap