All Callaham blocks are made of 1018 cold-rolled steel like the vintage originals, which contributes to the sustain and harmonic content that has made these guitars legendary. Replacing a block made of inferior materials (zinc, leaded steel, sintered steel) with one of Callaham's blocks will get you one step closer to those $30,000 originals. All have a precision-machined top surface that is free of paint to ensure solid metal-to-metal contact with the top plate, for optimal tone.
All Callaham blocks come with a precision-reamed Delrin insert in the arm hole, allowing the tremolo arm to fit snugly and be free of play, without requiring a spring in the hole as Fender's threaded blocks do. This gives you the best tremolo feel available, and no worries about losing springs (in case you're unaware of it, new Stratocasters ship with a round label over the hole in the tremolo - the label's purpose is to prevent the tiny spring from falling out and being lost).
The Delrin bushing is the feature that defines the Enhanced Vintage design (see next section below). Since Fender's threaded arms (or any arm with a 10-32 thread) can be used with Callaham's blocks, you're not forced to buy a Callaham arm for use with your Callaham block, but it is recommended (see illustration in the next section below to see why). However, because Fender's American Deluxe guitars come with a snap-in arm, the Fender arm is incompatible with Callaham's Deluxe block. For this reason, when you purchase a Deluxe block, a Callaham arm is included.
Callaham's blocks are machined with shallow string ball holes, like the originals. Blocks are marked for identification as shown in the photo above (from top: American Standard, Mexican, American Deluxe, Vintage)
