The best <$20 reef related equipment/purchase you've made:

Hey guys- lets discuss the best thing you bought for your tank under <$20! Preferably WITH a link too :)

Mine:

100 Pack of razors for only $6.49

http://ift.tt/1OB4g4N

Cable Label kit $8.99

http://ift.tt/1OB4f0N

Whats YOUR favorite?