Write compatible with DVD-R DL drives only
meaning
http://www.newegg.com/Product/ProductList.aspx?Submit=Property&Subcategory=5&Description=&Type=&N=100007589+600003707&IsNodeId=1&IsPowerSearch=1&srchInDesc=&MinPrice=&MaxPrice=&PropertyCodeValue=377%3A14697&PropertyCodeValue=377%3A31574&PropertyCodeValue=377%3A8665&PropertyCodeValue=377%3A19983&PropertyCodeValue=377%3A14241&PropertyCodeValue=377%3A29946
only.
or http://www.amazon.com/s/ref=sr_nr_n_0?rh=n%3A172282%2Ck%3ADVD-R+DL+drive%2Cn%3A!493964%2Cn%3A541966%2Cn%3A193870011&bbn=541966&keywords=DVD-R+DL+drive&ie=UTF8&qid=1332269633&rnid=541966
consider it a different type of DVD, like BLU-RAY