Can anyone tell me the inner diameter of jobo 2800 series print drums? Also the useable length of a 2830 drum, the useable length of a 2840 drum and the useable length of a 2870 extension model. I realise there are defined uses for these drums giving paper sizes but it would be useful to know the real dimensions as I may not be using standard paper sizes and we have some different paper sizes in the UK. The diameter is the most important for me. Thanks.