Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Outcome | Date | Tournament | Surface | Partner | Opponents | Score |
| --- | --- | --- | --- | --- | --- | --- |
| Runner-up | 5 August 2006 | Saransk , Russia | Clay | Dekel Valtzer | Alexey Kedriouk Orest Tereshchuk | 4–6, 7–5, [5–10] |
| Runner-up | 10 September 2006 | Brașov , Romania | Clay | Michal Navratil | Lazar Magdincev Predrag Rusevski | 4–6, 6–7 (9–11) |
| Winner | 4 November 2006 | Louisville , United States | Hard | Igor Sijsling | Amer Delic Robert Kendrick | w/o |
| Runner-up | 28 January 2007 | Wrexham , Great Britain | Hard | Richard Bloomfield | Thomas Oger Nicolas Tourte | 7–6 (7–4) , 5–7, [10–12] |
| Winner | 1 August 2010 | Cordenons , Italy | Clay | Rogier Wassen | James Cerretani Adil Shamasdin | 7–6 (16–14) , 7–5 |
| Winner | 28 August 2010 | Manerbio , Italy | Clay | Thomas Schoorel | Diego Junqueira Gabriel Trujillo-Soler | 6–4, 6–4 |
Question:
Which type of surface do Amer Delic Robert Kendrick's opponents have?
Answer:
Hard