Baader VariLock 29. Lockable T-2 Extension Tube. 20-29mm with spanner tool.
This very handy variable extension tube allows you to exactly set the distances between T-2 products such as coma correctors or reducers and your imaging or other optical equipment.
The engraved scale markings allow you to set the correct distance between 20mm and 29mm, then lock the tube tight at that distance with the included spanner.
The Varilock 29 is also perfectly suited for setting the correct spacing of the Baader RCC-I coma corrector onto DSLRs (36.5mm), and if that wasn't enough the included dovetail ring can also be added which enables the Varilock to be fitted to standard camera T-rings and used with DSLRs