Magnetic bookmark clips - I love using mine for my financial planning journal to separate debt, planning, and purchase tracking
 
Pairs perfectly with these stickers:
Girls Just Wanna Have Fund$
Piggy Bank
Cha-ching Coins
Girls Just Wanna Have Fund$ Phone Lock Screen (download)
Dollar $ign Phone Wallpaper (download) 
Monthly Financial Tracker Template (download)
New Money (Button/Magnets)
 
Size: 1 inch wide, 1.75 inch tall (folded)
1 inch wide, 3.5 inches tall (unfolded)