FHSP01 is our most popular bird spike and we have been exporting it more than 500000 meters yearly. 50cm length and 11cm spikes is the standard. we can make it 1 row, 2 rows, 3 rows, 4 rows or five rows as you can see in the pictures. Should you have any more question, please feel free to contact me at 13483838098 or fh01@fenghuihardware.com.