Ceramic polymer
From The Stargate Omnipedia
Flexible, ceramic-based shield plate developed by Dr. Bill Lee and his team of scientists at Stargate Command as an improved defense for S.G. personnel in dangerous territory. The polymer is an improvement over Kevlar, which does not protect against Jaffa staff weapon blasts (instead, it essentially "cooks" the wearer like an oven). It resists a staff's plasma heat, stops plasma blasts, and fits into any standard S.G. field unit vest.
KEY EPISODES
Heroes, Part 1 - Dr. Lee introduces Emmett Bregman's camera crew to his team's new ceramic polymer.
Heroes, Part 2 - The ceramic polymer protects O'Neill after he gets shot in the chest by a Jaffa on P3X-666.