A set of 3 saxophone side key risers in solid wood. These are available for Yamaha (which covers most other modern saxophones) and vintage Selmer.
Install using epoxy (sold here) to secure these. It provides an amazing hold, with the ability to release with heat if necessary. I recommend asking your technician to install these.
Finding Your Side Key Riser Height
Side key risers aren't one-size-fits-all. The right height depends on your saxophone, your key setup, and your hands. Here is how to measure your fit before you order.
What you'll need: a roll of painter's tape and a ruler.
Step 1, build your shim. Stack layers of painter's tape on top of one of your side keys. Play a few notes and adjust, adding layers if the key still feels too far and taking them away if it feels stiff or cramped, until your hand feels relaxed and the key responds naturally.
Step 2, measure the stack. Measure the height of your tape stack. That is your number. You only need to measure one key, since the risers come as a set.
Step 3, order. Match your measurement to the sizes below.
Small, adds around 6mm (1/4")
Medium, adds around 8mm (5/16")
Large, adds around 10mm (3/8")