Twist-off Bottles & Twist-off Caps
Twist-of bottles are made to be capped with a completely different type capper than is available to homebrewers. They are generally made of a much thinner glass than the pry off bottles. When using twist-off bottles with a home capper, some of the bottles may not seal properly resulting in flat or poorly carbonated beer. Therefore, twist-off bottles should only be used in an emergency.
Twist-off caps which have the arrow showing which way to twist are made of a thinner medal than pry-off caps. They will still seal a pry off bottle properly with on loss of carbonation. But, they won’t twist off. So, it’s fine to use them.