I'm not 100% sure of the model but having taken advice and searched the internet it seems most likely to be a BC800W. Can be used as a straight stand or a boom stand, and folds up to a useful size.
Pearl cymbal boom stand BC800W in very good condition
Vintage Pearl Heavy Duty Cymbal/ Boom Stand - **NO BOOM**
20” Pearl Ride Cymbal with Boom Arm Cymbal Stand. Free UK P&P.
Pearl like CH70 Cymbal Boom Arm and Clamp CBCSet 03 Millennium
Pearl Cymbal Boom Arm with Clamp / Drum Hardware #VO48
