The above Hon 310 is Charcoal and is 26-1/2"Deep and the Hon 510 is not available in Charcoal, and the size is 25"D, other than that the file cabinets are the same. For pricing and availability please contact Customer Service. They will be glad to help with your question. You may contact them at http://www.staples.com/sbd/content/help/contact/index.html
or by phone at 800-333-3330. Thank you for your inquiry.
Answered on 3/5/2012 by Chrsitina.M from Staples