Thirty-nine people have already placed a bid on the sling, going for $1,625 as of 6 p.m. Thursday.
As stated in the eBay listing, the money will benefit the abused and neglected animals cared for by convicted inmates in Arpaio's MASH unit.
A photo of Arpaio used in the listing showed the Sheriff autographing the sling while in his Phoenix office.
In February, Arpaio, 80, tripped and fell, breaking his left shoulder. He wore the sling for several weeks to help it heal.