Loxx strap locks are the very best I've found over the decades.
https://www.thomann.de/nl/loxx_security_lock_gd.htm?msclkid=e35230d12d7e14bb51b455a07292edd9&utm_source=bing&utm_medium=cpc&utm_campaign=Shopping NL&utm_term=4576167415641879&utm_content=GI
Flat fit, strong, lasting and secure, no squeeking and faster to click on and off than the Grolsch washers.