﹥ Coding principles for uncoated ball lens cap ﹥ 33GB1515H227C100 (TO33 CAP) Hermetic sealing ﹥ 56GB2020H270C150 (TO56 CAP) glass to metal seals/Hermetic seals ﹥ 56GB2018H297C100 (TO56 CAP) Hermetic seals ﹥ 56GB1515H297C100 (TO56 CAP) Hermetic seals