Wholsale Closeout Square Notch Steel Trowel. RIDGID introduces the 1/4 in. x 1/4 in. Square Notch Trowel. The 1/4 in. x 1/4 in. square notch trowel is used to spread thin set mortar when setting trowels. The ergonomic wood handle provides the pro comfort and control. Ergonomic wood handles provides comfort and control 1/4 in. x 1/4 in. notches High impact Easy to grip, wooden handle RIDGID: Powerful. Durable. Professional.