Sentence:  The most notorious squeezes have names: the Gun Barrel, Jam Crack, the Electric Armpit Crawl, Devil's Pinch. You can even train for them by buying a product called a <WSD>Squeeze Box</WSD>. It's essentially a play torture chamber for cavers, a wooden box, about thirty by thirty inches, open on the two ends. You set it up in your living room, get down on your hands and knees, and crawl through it. No problem. But the box has adjustable sides and top. You loosen the bolts, lower the lid, slide the sides closer, crawl through again. ... Though a <WSD>Squeeze Box</WSD> may be good practice for learning how to squinch through small places, doing it on your living room carpet, ... just doesn't duplicate what causes the panic. 
Meaning of the word marked with <WSD> tags:  A box with an adjustable opening used by cavers to practise crawling through tight spaces.