Neck Screw, mouthpipe screw. Bach Flugelhorn (FH200), Selmer Saxophone, & others, 8-32-1/2 brass neck screw.
Neck Screw. Sousaphone & Marching Tuba. Bach Flugelhorn (FH200), Selmer Saxophone, & others, 8-32-1/2 brass or nickel neck screw.
Mouth Pipe Screw. Hard to find, Old sousaphone lower mouthpipe screw, brass 10-32 tpi.