1. TEKCAM Bike Fork Stem Extender Aluminium Alloy Handlebar Riser Adaptor for Mountain Bike Folding Bike Road Bike BMX (Click Link to Check Price on Amazon)
Editor's Rating : 9.8 out of 10
Comes with 4pcs gasket,can increase the height up to 70mm/2.75inch.And you can freely adjust the gasket to fit your comfortable position.This bike extender can help your handling more flexible,easier to force when climbing. Lightweight, operation is comfortable.

2. WEANAS New MTB Bicycle Bike Aluminium Alloy Handlebar Stem Riser 1-1/8" Rise 28.6 x 117mm Black (Click Link to Check Price on Amazon)
Editor's Rating : 8.9 out of 10
WIDELY COMPATIBLE - Work on mountain or road bikes with 1 1/8" threadless steering tube.ADJUSTABLE - 1 x 3/16 and 3x 3/8 Spacers included to allow you to adjust the handlebar to be rasied to your comfortable position.

3. Delta Cycle Alloy Bicycle Stem Raiser (Click Link to Check Price on Amazon)
Editor's Rating : 9.4 out of 10
Allows for adjustment of up to 3 1/2" of stem heightWeighs 189 grams

4. Aluminium Alloy with Carbon Fiber Mountain Road Bicycle Handlebar Bike Stem 6 Degree 100MM 1 Pcs (Click Link to Check Price on Amazon)
Editor's Rating : 9.7 out of 10
HIGH QUALITY: Aluminium alloy with carbon fiber, durable and long life time guarantee.FEATURES: Easy to install and use. Exquisite workmanship. Four bolt bar clamp holds bar securely in position.

5. ZTTO Bicycle Stem Extender Handlebar Riser Head Up Adapter 28.6mm/1.13 inches (Black) (Click Link to Check Price on Amazon)
Editor's Rating : 9.4 out of 10
Weight: 220gMaterial: Aluminum