In one example of the disclosure, a developer system includes a housing and a developer roller. A first electrode and a second electrode are disposed in the housing, the first and second electrodes to create an electrical charge to cause transfer of printing fluid to a developer roller surface. The developer roller is rotatably connected to the housing. The developer includes a surface, a bearing to support and enable rotation of an axle attached to the developer roller, and a plurality of stop pins. The plurality of stop pins are connected to the housing. The stop pins are to support the bearings and to establish target distances between the developer roller surface and the first electrode and second electrodes.