BrickLink - Part 61927c01 : LEGO Technic Linear Actuator with Dark Bluish Gray Ends, Type 1 [Technic] - BrickLink Reference Catalog
LEGO® 6240630 40918c01
UPDATED] Lego Technic linear actuator performance measurement (including new XL actuators) - LEGO Technic, Model Team and Scale Modeling - Eurobricks Forums