Used in ballistic tests, a witness block is a massive slab of metal located behind a test subject which totally stops further progress of projectile and impact subjects . Example of witness block material: duralumin cylinder.[1]

References

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  1. ^ R Klement; S Rolc; R Mikulikova; J Krestan (2008). "Transparent armour materials". Journal of the European Ceramic Society (ECERS). 28 (5): 1091–5. doi:10.1016/j.jeurceramsoc.2007.09.036.