Milwaukee 2-1/2 in. Universal Fit Diamond Grit Grout Removal Multi-Tool Oscillating Blade (1-Piece) 49-25-2271 - The Home Depot
How to Choose the Right Blade for an Oscillating Tool or Multi-tool - YouTube
How to cut tile using an oscillating tool: Toilet Drain Hole - YouTube
Fein StarLock Carbide Oscillating Saw Blade - Extra Thin for Removal of Defective Tile Grout and Making Cuts in Plaster - Fits Most Multitools - 63502125210 - Amazon.com
DEWALT Oscillating Fast Cut Carbide Grout Removal Blade DWA4220 - The Home Depot