Brickset: A history of Technic pins | New Elementary: LEGO® parts, sets and techniques
LEGO Technic Through Axle Connector with Bushing - Pack of 8 (32039 / 42135) | eBay
Amazon.com: Gobricks GDS-1029 Technical, Axle and Pin Connector Perpendicular Split compatible with lego 92907 All Major Brick Building Blocks Technical Parts Assembles (191 Bright Light Orange(036),400PCS) : Toys & Games
New LEGO Technic Axle & Pin Connector Perpendicular Triple (x10) 63869 Black | eBay
Lego® Technic 42003 Axle and Pin Connector (red)
Smartable High-tech Axle Connector Pneumatic T-piece Building Block Moc Parts Toys Compatible City 99021 30pcs/set - Blocks - AliExpress