1 m is too long to drive, 50 cm or less will result in insufficient fixing strength. Because it is round, it is easy to drive, and when pulling out it twists with another iron pile and comes out. It is the easiest to use, with high rupture strength as it is jagged. Since 10 bottles are packed, it is good to purchase in ten units. It is heavy so I really appreciate being able to send it to the site without going to the home center. I ordered 80 bottles, but it arrived the next day so I really appreciate it.