eBay

Tools -T161320 Trade 1/8" Hard Plastic Spacers 'T' (Pack of 500)

Hard plastic - does not compress
1/8” are hollow allowing thin set through
Can be used as leave-in spacer

Ox trade Tile spacer - hard 'T' | 1/8 inch | 500 pieces/bag, 1/8” spacers are hollow allowing thin set through, made in China