Harley introduced 300mm front discs in 2006 on V-Rod models. In 2008 these 300mm discs were adapted on FLH and FLT series models. These V-Rod and Touring models utilize a smaller bore brake master cylinder. In order to optimize braking performance on those models, PM created smaller volume calipers based on the proven symmetrical bore 125x4B design. Customers who prefer differential bore PM 4 or 6 piston calipers on their bike must upgrade from the stock 15mm bore brake master cylinder to an 11/16" bore for optimal performance. Calipers fit front 2006 thru 2017 V-Rod, 2008 to present Touring, 2015 to present Softail and 2014 to present Sportster and are sold each.