A stir bar is definitely something you'll want to have a spare of! Seasoned homebrewers know the value of being prepared and having spare parts. This 1" magnetic stir bar works great as a great backup or as a replacement.
Whether you need to make an extra starter, or you accidentally pitch the slurry with the magnet bar still inside, or just plain lose it you’ll be relieved to have an extra magnetic stir bar on hand.
I've used 2" bars and bars with the "stabalizer ring." The ring only makes the bar clang all the while it's spinning and the larger the bar the more frequently it gets thrown. These 1" bars are perfect and can work at higher RPM of the other bars. Can't beat em'!
I use this in both my 1L and 2L flasks. Easy to clean, stays where I want it in the flask. Keeps the starter humming along. Tip: use a small magnet on the outside of the flask to hold the stir bar in place when you dump your yeast into your fermenter.
I have used this for my smaller starters (up to 1.5 liter) and even used this in a 1 gallon mead batch. A 2" would have worked better with the mead, but it wasn't thrown and it was in use for a month strait.