1/4″ hex shank countersinks are fine for a quick drill. They don't slip in drill chucks. You can make deep countersinks easily by setting the countersink's depth stop to allow the countersink to drill more deeply into the worksurface.
eBay
19pcs Titanium-Coated Drill Bit Set with 135° Tip, Hex Shank for Wood, Soft Metal & Plastic (1/16"-1/4") - Quick Change
Aliexpress UK
Material: High Speed Steel HSS. Shank type: round. 6x Drill Bit. Hardness: 65. Sizes: 6.3 8.3 10.4 12.4 16.5 20.5mm. Any special request cannot be accepted after.
eBay
1 Pc Spiral Pole Auger Set Garden Planting Flowers Plant Supplies Loose Soil Digging Hole Metal Drill Bit Garden Power Tools
Aliexpress UK
Complete Set: This premium 4-piece countersink drill bit set features M2 high-speed steel tapered guide drills in sizes 2.8mm × 8mm, 3.2mm × 8mm, 3.5mm × 10mm, and 4.0mm × 10mm. Automatic Wood-Stop: The upgraded countersink drill is constructed entirely from aluminum alloy with built-in bearings.
eBay
Metal Mechanics Drill Bit for Making Three-Way Holes on Steel PVC and Gypsum Boards 25-120mm
Aliexpress UK
1Pc WiFi 6 6E Tri-Band Antenna 6GHz 5.8GHz 2.4GHz For ASUS ROG STRIX MAXIMUS. Multi-Pin Plug PTT Mic Headset For Motorola DEP550 DEP570 DP2000 DP2400 DP2600 B. You may also like.
eBay
XCAN End Mills High Speed Steel M2 Metal Cutter 2 Flutes Straight Shank CNC Router Bit for Wood Aluminum Steel 2-12mm
Aliexpress UK
Material: High Speed Steel HSS. Shank type: round. 6x Drill Bit.
eBay
13PCS Metric Drill Bit Set 3/16 to 1/2 Inch for Glass Metal Tile Concrete Masonry Professional Electric Drilling
Aliexpress UK
Material: High Speed Steel HSS. Shank type: round. 6x Drill Bit.
eBay
13Pcs Metric Masonry Drill Bits Set 3/16”-1/2” Tungsten Carbide Tip for Glass Metal Tile Concrete Professional Drilling Tool
Aliexpress UK
1 Countersink Drill Bit Set. The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness. The slot markings are clear and wear resistant .
eBay
13pcs/set Drill Bit Set 3/16 to 1/2 Inch for Glass Metal Tile Concrete Masonry Electric Drilling Kits
Aliexpress UK
Countersink set with three countersink drill bits (12mm, 16mm and 19mm) and driver handle. 3pc Countersink Set. 3 x 90° Countersink Bits: 12, 16 & 19mm. Handle accepts all other 1/4″ hex accessories.
eBay
Carbide Rotary File Arc Metal Cutter Bit Tungsten Hard For Aluminum Stone Plastic Carving Engraving For Metalwork
Aliexpress UK