Manchester United are inviting bids for a series of photos featuring their legendary former manager, Alex Ferguson, and several players in an auction to raise money for UNICEF to protect vulnerable children in Vietnam.

Guests are invited to bid on the photographs, each of which was personally chosen and signed by Sir Alex and other prominent players featured in the photos such as Paul Scholes, David Beckham, Cristiano Ronaldo, and Ryan Giggs, according to the auction website.

“These images represent an iconic era of the football club and would be an incredible piece of memorabilia for any Manchester United fan,” the website said.

In “The Prodigy,” one of the photos on auction, Sir Alex has a hand on Cristiano Ronaldo’s shoulder, while the former United striker smiles broadly.

The photo was signed by Ferguson and Ronaldo, and is displayed on the auction website with a quote by the ex-manager, reading “The best player I managed during my time at United. Cristiano Ronaldo was a joy to work with.”

The current bid for the photo is £2,550 (US$4,111).

The auction is the first in a series of activities organized to mark the 15th anniversary of the United for UNICEF partnership, which has raised over £3 million ($4.9 million) and helped more than 3.4 million vulnerable children worldwide.

The celebratory activities are also being held to “commemorate the longest running partnership between a sporting organization and a global children’s charity,” the English Premier League club said on its website.

Ferguson, who managed Manchester United from 1986 to 2013, has been working as a UNICEF ambassador since 2002.

He retired as manager of the club on May 8, 2013, after 27 years of success with 38 trophies, including 13 Premier League and two UEFA Champions League titles.

“UNICEF is such a great partner of Manchester United and the work they do is exceptional; they deal with poverty, child abuse and exploitation, so the support they receive from Manchester United is really important,” Ferguson was quoted on the club website as saying.

Money raised from the auction will help fund UNICEF’s work in protecting vulnerable children in Vietnam from abuse, neglect and exploitation.

The auction was launched on Tuesday following an invite-only event attended by a host of esteemed guests and friends of the club, including Eamonn Holmes and Paddy Crerand.

It will continue online at www.united4unicef.org until October 5.