They will be the same as the ones used for the Pen Displays. I have listed the SKUs below for the two types of nibs that Xencelabs offers.
Standard Black: XMPN10
Link: https://www.xencelabs.com/us/store/accessories/standard-nibs-v2
Gray Felt: XMFN10
Link: https://www.xencelabs.com/us/store/accessories/felt-nibs-v2
Please note: If you have the first-generation Pen Tablet, the nibs for those pens are longer and may damage the pen sensor of the v2 Pens.
For further assistance or inquiries, contact the Xencelabs Customer Care team at CustomerCare@xencelabs.com.