If you have a 25mm wide strap, you need to buy a 25mm loop. Very good quality.
CS Osborne Nickel Semi Professional Eyelet Kit Nickel Plated Solid Brass Eyelets
Solid Brass Dunham Full Belt Buckle For 1.5" - 38mm Wide Strap Brass or Nickel
30mm Belt Buckles – 11 Styles in Nickel Plated & Solid Brass (Silver Finish)
Nickel Plated Solid Brass Eyelets & Washers Handy Pk (24 of each part)CS Osborne
30mm Belt Buckles – 19 Styles in Nickel Plated & Solid Brass (Silver Finish)
CS Osborne Brass Semi Professional Eyelet Kit - Solid Brass Eyelets