The 10K Series mouthpieces are the culmination of Clark's 30 years of experience as a mouthpiece maker and 10,000 handcrafted professional mouthpieces sold. These mouthpieces are computer machined from excellent German rod rubber. Clark has designed these mouthpieces for beauty of sound, response and excellent intonation. The 10K series mouthpieces are expertly manufactured for me by master craftsman Wesley Rice of Rice Clarinet Works.