#7 Holders are only for use with T-type blades shown below; or with bevel (wedge-shape) blades having parallel top and bottom edges, as shown below.
For bevel (see drawing) as well as T-type blades. Enables you to cut-off close to chuck.
Absence of vibration prevents breaking blades.
Aloris AXA#7 Quick Change Parting Blade Cutt Off Holder