(1)--- MULTI-USE BLADES: 48,60,80, 100 & 120 teeth blades are handy for ANY job such as: Pruning, Hedging, large Limb cutting as well as for Brush & Brambles. MORE teeth means more aggregate cutting surface (more carbide) and therefore less seizing in limbs and less tearing and ripping when hedging (best at high rpm's)...... (2)--- BRUSH & BRAMBLES specialized BLADES: Our 36 & 40 teeth blades are more tailored for Brush & Brambles due to deeper teeth cavities. LESS teeth are required to create deeper wider teeth cavities, that can grab & cut more brush material per blade spin (best at alternating rpm's). (3) Diameter 9" 10" are available.