The ChiaoGoo SPIN interchangeable 4 inch "S" tips are the same bamboo needles that you know and love. 4 inch tips were manufactured to be used with the cords to make 16 inch circulars.
Sold as 2 tips per package.
The "S" tips are only compatible with other "S" products. The "L" tips are only compatible with other "L" products.
ChiaoGoo interchangeables are not compatible with Knitter's Pride interchangeables.