squeeze box

Short definition from Wiktionary

Noun

1. 1
   An accordion or concertina.
2. 2
   A box with an adjustable opening used by cavers to practise crawling through tight spaces.
3. 3
   A container that fits tightly around an animal to immobilize it for medical treatment, transportation, etc.
4. 4
   Synonym of hugbox (“a therapeutic device”).
5. 5
   Alternative form of squeeze box.