Tele Vue Optics M54 Camera Adapter for 2.4":

Seamless Accessory Integration

Dual Thread Design: Features an M54 x 0.75mm male thread on one side and a 2.4" Tele Vue imaging system thread on the other for versatile connections.
Accessory Compatibility: Ideal for attaching M54 threaded accessories to the Tele Vue imaging system.
Compact Path Length Usage: Occupies only 0.26" / 6.6mm of path length, maximizing efficiency when used with other Imaging System accessories.
Astrophotography Essential: A must-have for astrophotographers seeking to expand their setup with various accessories.