These S4 rollers have a bearing on the tip that will be a great upgrade to any of Der Jung's sets. The bearing is 13/32 inches or 10.2mm - slightly larger than the standard 10mm hole. The rollers are sold in sets of 6 and come with 6 extra spring washers to compensate for variations or inconsistencies in plate thickness.
I have tested some of these string for the manufacturer for the past two years and have been very impressed with the sound that they are acheiving with their proprietory bass string technology. Truly there are still new frontiers in the making of guitar strings and we can never take for granted how that influences the making of our guitars and our techniques in playing them. Paired with normal tension carbon trebles, these "Inspiro" strings deserve test drive on your guitar.
This is my "go-to" humidifier that I provide with all of my new guitars when shipping them to their new homes. Fill them with distilled water and the chrystals inside will retain moisture and humidify your instrument while in the case. Given that moisture molecules travel 1,400 miles per hour and are lighter than the air we breathe, it's best to just use a humidifier and not kid yourself into thinking your case is going to keep your guitar from equilibrating with an excessively dry climate.
Here is an affordable and effective clip-on tuner for your guitar that has a full color LCD display. Battery and directions are included.