Most stands adjust via friction clutch or adjustable knob.Friction clutch: With a friction clutch, you simply push up or pull down on the music stand to adjust it. Friction clutches are usually stronger than knobs, last longer, and cost more.Adjustable knob: With adjustable knobs, you simply turn the knob to unlock it, adjust the stand height, and then tighten the knob. While not as durable as a friction clutch, adjustable knobs can meet the needs of musicians who seek an inexpensive stand.