Biological indicator vials are easy to use and interpret with visual color readout in 48 hours. Self-contained biological indicators significantly reduce possibility of contamination, minimizing false positives and assuring more accurate results. 48 hour result (green cap) biological indicators and test packs for ethylene oxide sterilization cycles. The 3M Attest self-contained BI for all EO cycles consists of a Bacillus atrophaeus spore strip; sealed glass ampule with growth medium and bromothymol blue pH indicator dye system; green color-coded cap with holes for sterilant penetration and a filter as a bacterial barrier, and a chemical indicator on the label that changes to green when processed. After sterilization, the vial is "crushed" to join the growth media with the processed spore strip. The BI is incubated for 48 hours for a visual color change readout. A color change to yellow indicates surviving spores and a positive result.