These can go on T-shirts, Longsleeve T-shirts, Tanks, etc.
Most items can be neck-tagged as long as the interior of the item isn't fleece like with Sweaters / Hoodies.

Inner neck tags are typically done as digital print or silkscreen, depending on the order size or customer preference.

Discharge printing can be done on most apparel, so long as the item is 100% cotton.
There is a variety of considerations and variables when pricing discharge but a good rule of thumb is that it's +3$ per item as compared with basic printing prices.

Waterbase printing can be used on any type of apparel, it's versatile and great for fashion lines looking for a soft print.
There is a slight discount as compared with discharge inks

Sewn neck-tags are a great solution for fleece products, T-shirts and even as visible decoration while shirts are being worn, as is the case with hem-tags.
Sewn tags are typically only done on wholesale orders of apparel over 250 units, given the high set-up costs.