CHEAPEST ON EBAY!
A dial of 7 red and 7 blue (new style).  These are commonly used in a number of manufacturers in-the-ear products, particularly Siemens and ReSound.  

Comes with insertion / extraction tool. Blue denotes for use in left hearing aid, red for use in right-ear hearing aids.  

These gauze-based filters are acoustically transparent and prevent cerumen (wax), dirt and moisture from penetrating the hearing aid via the receiver opening at the end of the hearing aid. In in-the-ear, and receiver-in-the-ear hearing aid designs, the receiver is the electronic component inserted the deepest into the ear canal, and therefore should be offered the most protection.  HF3 wax guards can be easily taken out and exchanged using the integrated changing tool.

If you have any questions or would like to bulk buy let me know.
IF you find it cheaper let me know and you will get better price