The green glass door

The "Green Glass Door"
The Green Glass Door is a game were you must figure out the rule for what can fit and what can not fit. There is a rule for each. You use the fraise " will fit through the Green Glass Door, but  will not. This is a fun game to play on hikes in the woods. There is a discussion on what you think that rule is at

http://troop30knoxville.wikia.com/wiki/User_blog:Bsat30historian/Green_Glass_Door

!SPOILER ALERT!

You can find the answer at

https://www.braingle.com/brainteasers/teaser.php?op=2&id=2293&comm=0