The weight of the earth and of the heavy equipment used to dig graves far exceed what an unprotected casket can withstand. For this reason, you may wish to purchase a burial vault, which is a sturdy outer container designed to protect a casket. 
   Casket vaults are made of concrete, plastic or metal, and are used primarily to prevent the weight of the settling ground from crushing the casket.

Gold painted non-reinforced concrete container.
No inner liner. Limited seal.

  Single reinforced with Strentex plastic. Full seal.
  Gold coloured.

Strongest single reinforced vault in the Wilbert line,
using ABS Marbelon. Limited seal. Gold/cream base,
with marble-like cover.

  Double reinforced, lined with ABS Trilon and
  stainless steel. Full seal. Black/silver base,
  with stainless steel cover.

Double reinforced, lined with ABS Trilon and stainless
steel. Pink on white base, with stainless steel cover.

  Double reinforced, lined with ABS Trilon and
  solid copper. Full seal. Black/copper base,
  with copper cover.

Finest double reinforced vault in the Wilbert line, lined
with ABS Trilon and bronze. Full seal. Black/bronze base,
with bronze cover.