O-RING 

For gray fitting 3"
# 01300156 2 7/8" I.D. * 3 1/8" O.D. 1/8" WALL

For old style ss releaser cover 6"  
# 01280173 5 1/4" I.D. * 5 1/2" O.D. 1/8"WALL

For old style ss releaser cover 6"  and big blue filter  
# 01280175 5 1/2" I.D. * 5 3/4" O.D. 1/8" WALL

For manifold 6" and releaser pump casing 6"  
# 01280072  6 1/4" I.D. * 6 5/8" O.D. 3/16" WALL

For manifold 8" and moisture trap 8"
# 01300188 8 1/2" I.D. * 8 3/4" O.D. 1/8" WALL

For older moisture trap 10" and booster
# 01280039 9 1/2" I.D. * 9 3/4" O.D. 1/8" WALL

For moisture trap 10"
# 01280531 11 1/2" I.D. * 12 1/2" O.D. 1/2" WALL

For moisture trap 15" and releaser 15"
# 01280090  14" I.D. * 14 3/8" O.D. 3/16" MUR

For old style white "belly" releaser 
# 01280168 

For releaser and moisture trap 20"
# 01250345 18"I.D. 19" O.D. 1/2" MUR