These are very small pieces - Micro K'nex, not standard size K'nex.  These pieces are commonly used in many K'NEX Roller Coasters and other Micro sets.  These are shown in the second photo with a larger standard size piece for reference only, not included.  You will receive 50+ micro K'nex end caps with each lot purchase.  

Buy from us with confidence! I am a lifelong avid K'NEX builder.  I know the parts well and have a huge selection.  Please feel free to contact us with any questions, or if we can be of any help finding a specific part for you.  I would be happy to put together bulk lots of any part and quantity that we have available.  Thanks for looking!