These corner connectors are an easy and sturdy way to fix two pieces of V-Slot extrusion together.
They're machined from a solid block of aluminium, which means they're very, very strong! They're then anodised black for a nice surface finish, and can bring the understated and professional look to any build. We also have cast aluminium brackets available (check the related items) - they're not quite as strong, and not quite as pretty - but they're a tad cheaper, and strong enough for most jobs.
You'll likely want to pair these connectors with two 8mm M5 low profile screws and two M5 T-Nuts if you're using them to join two lengths of V-Slot.