Yes, this kit is sufficient for small RNA. However, It is worth noting that small RNA molecules, such as microRNA, siRNA, tRNA, 5S rRNA, are not efficiently recovered using the standard procedure. If desired, these small RNA molecules can be recovered by increasing the amount of binding solution, as described in Protocol A under Procedure Step 4.
For more information, please see the protocol associated with this product:
https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/323/177/strn250bul.pdf