When you choose a rubberquality it is important to know what substanses your profile will be in contact with. Against only normal weather, EPDM is the quality to choose.
If the profile is in contact with chemicals, neoprene (CR) quality  is the right quality.
Against oil and petrol Nitril (NBR) quality is the best choice.
There is also a flameresistant quality which is frequently used offshore.

The hardness is measured in shore A (shA) on the scale of 1-100. For comparison - summertyres for cars have for example around 60o sh.A.

Spongerubber (with closed cells) is a type of rubber containing aircells. This is different from spongerubber with open cells which is not water tight. Spongerubber can also be produced with skin (extruded spongerubber). This type will be more robust against tares, rips and other external damages. Extruded spongerubber with skin has a hardness of around 60o sh.A.

Here is a list of the most common qualities:

42-301 Neoprene (CR)  ekstruded spongerubber ca. 20o sh. A
43-333 Neoprene  (CR) 30 o sh. A
43-334 Neoprene  (CR) 40osh. A
43-335 Neoprene  (CR) 50osh. A
43-336 Neoprene  (CR) 60osh. A
43-337 Neoprene  (CR) 70osh. A
43-338 Neoprene  (CR) 80osh. A
43-435 Nitril (NBR) 50o sh. oilresistant
43-437 Nitril  (NBR) 70o sh. oilresistant
43-536 EPDM 60o sh.A
43-537 EPDM 70o sh.A
43-304-X Flameresistant neoprene (CR) 40osh.A
43-386-X Flameresistant neoprene (CR) 50osh.A
43-336-X Flameresistant neoprene (CR) 60osh.
Spongerubber without skin: ca. 13o sh. A
42-300-20X Cut spongerubber  Neoprene (CR)
42-300-21X Cut spongerubber  Epdm
42-300-22X Cut flameresistant spongerubber Neoprene (CR)
42-300-23X Cut flameresistant spongerubber Nitril (NBR)