You can choose between 3 different sizes of extensions for your SG-L and your SG-LX:
SG-L and SG-LX Size 3-6 come with 50mm) and 60mm) extensions, the latter is pre-assembled. SG-L and SG-LX Size 7-8 come with 60mm and 70mm extensions, the latter is pre-assembled.
Caution: When exchanging extensions, always use the new screws which are part of your purchase. Each set comes with 8 screws incl. screw-nuts.
Check screws regularly. If necessary, retighten.