This is a Crain 152 Stair Bolster Tool which is 4"/100mm wide.It has a soft grip handle that makes it conformable in the hand. Made by Crain Carpet Tools. The edge of the bolster is not straight - see pic of example.
eBay
Galaxy Earth Moon Round Carpet for Children’s Room Floor Carpets Mat Home Decor Living Room Anti-Slip Bedroom Carpet Area Rug
Aliexpress UK
The Carpet Tucking tool is ideal for getting the floor covering under door trims and tucking down in difficult small areas. 18cm x 5cm x 2.5cm with a slim 1mm edge. Also has a metal top of the handle.
eBay
12pcs Black Carpet Gripper Pads -Carpet fixing sticker- Reusable & Washable Carpet fixing sticker for Hardwood Floors Tiles
Aliexpress UK
3 Piece Carpet Fitting Kit with Knee Kicker / Bolster / Cutter. Voche® Carpet Knee Kicker Professional Fitting Tool is an essential tool required for fitting carpets. This Professional Carpet Kicker features heavy duty steel construction for durability.
eBay
Household Heart Shaped Carpet Bedroom Living Room Soft Comfortable Plush Carpet Mat Artificial Family Non Slip Practical Carpet
Aliexpress UK
The Carpet Tucking tool is ideal for getting the floor covering under door trims and tucking down in difficult small areas. 18cm x 5cm x 2.5cm with a slim 1mm edge. ✅ 1mm tucking edge. ✅ Use on carpet and vinyl.
eBay
Decoration Rug Mat Bedroom Carpet Room Carpet H-hello Kitty Doormat Rugs Carpets Entrance Door Mats Home Choice Foot Bath Floor
Aliexpress UK
ThisHeavy Duty Carpet Knee Kicker is the ultimate tool for seamless carpet installation with precision and ease. Heavy Duty Carpet Knee Kicker.
eBay
8Pcs Home Floor Rug Carpet Mat Self-adhesive Anti Slip Reusable Fixed sticker carpet carpet mat adhesive tape corner mat
Aliexpress UK
Puller Clamp Carpet Claw ?. Carpet Fitting Tool. Designed to assist the installer when removing stuck down flooring materials from sub floor. Powerful jaws operate on the lever system, the harder they are pulled the tighter they grip.
eBay
1.5 Meters Wide Red Carpet LGOLOL Wedding Carpet Disposable Long Runers Exhibition Carpets Wholesale Staircase Corridor Rugs
Aliexpress UK
Voche Pro Knee Kicker Carpet Fitting Tool. ThisVoche Pro Knee Kicker Carpet Fitting Tool is an essential tool required for fitting carpets. This Professional Carpet Kicker features heavy duty steel construction for durability.
eBay
VIKAMA Bohemian Vintage Crystal Velvet Carpet Home Bedroom Carpet Large Area Living Room Sofa Coffee Table Mat Large Size Carpet
Aliexpress UK
Carpet fitter's bolster, especially useful when fitting carpet on stairs and around skirting boards. An essential tool for all carpet fitters when the need for tucking carpet on stairs or grippers is required.
eBay
1Roll Carpet Floor Tiles, Peel and Stick Carpet Flooring Roll, Non Slip Absorbent Carpet Mat for Any Place
Aliexpress UK