The primary use of the expansion shells is to mechanically point anchor roof bolts and cable bolts. Expansion shells are excellent for immediate support where grout and resin installations are difficult. Post grouting after installation is possible. The expansion shell has a leaf locking system to allow pre-tensioning on the chosen support. The expansion shell comes in various diameters. Spring loaded systems are also available.Various internal thread sizes and types are available upon request.vailable upon request.