http://http://voelkl-snowboards.com/index.cfm/EN/352specs
RT SL 153 RT SL 158 RT SL 162 RT GS 168
contact length 1345 1395 1435 1495
length in mm (tip/tail) 140/45 140/45 140/45 140/45
height in mm (tip/tail) 36/5 36/5 36/5 36/5
width in mm (tip/waist/tail) 247/187/242 255/195/250 255/195/250 244/190/239
inserts (pcs/setback in mm) 20/30 20/30 20/30 20/30
stance in cm (min/med/max) 42/46/50 44/48/52 45/49/53 46/50/54
sidecut 8,10/Direct Race 8,95/Direct Race 9,20/Direct Race 11,00/Direct Race
rider's weight in kg <75 50-75 55-80 60-85
RT GS 173 RT GS 178 RT GS 183
contact length 1545 1595 1645
length in mm (tip/tail) 140/45 140/45 140/45
height in mm (tip/tail) 36/5 36/5 36/5
width in mm (tip/waist/tail) 244/190/239 244/190/239 244/192/242
inserts (pcs/setback in mm) 20/30 20/30 20/30
stance in cm (min/med/max) 46/50/54 48/52/56 48/52/56
sidecut 11,80/Direct Race 12,60/Direct Race 13,00/Direct Race
rider's weight in kg 65-90 70-95 >75
Not sure how the post is going to turn out, but the website list the current alpine offering from Volkl as single radi sidecut boards.