A crossover sub is used to crossover from one connection size to another or as the disposable component used to extend the connection life of a more expensive drill stem member.
Crossover subs are available with:
1. box x pin
2. box x box or
3. pin x pin connections.
Crossover Subs are manufactured from 4145H alloy steel. The connections are protected by a phosphate surface coating that minimizes galling on initial make-up.