Flea collars are a no no

If you use a collar  which I recommend since you need id tags on the
furballs  make sure it was a break away collar they run from $3 to $10

I saw that you go the furball fixed GOOD GOING  very responsible of you.

Did you get all the vaccines needed

Plus since you are not used to having cats  make sure you use advantage( my
choice and recommendation ) to control fleas

I do not trust them myself even though they have elastic on them to release
cat should he/she get caught, fleas can be known to breed under the collar.
I live in the UK so flea treatment I get from the vet, the pet stores here
are only licensed to sell certain types, that the fleas are immune to.  My
choice is frontline every 6 weeks.  They tend to ease off in the colder
weather.

Per Nan:

I got one for ours: name tag, phone number and all.

After losing a little blood trying to get it on - and observing that one of the
neighbor's cats loses his several times a year, I came up with the following
rationalization:

There are several cats in the neighborhood that look more-or-less exactly like
ours.   What if ours winds up clawing the daylights out of somebody's kid?   Do
I want a collar on it with our name and phone number?  Or do I want it to be
indistinguishable from three or four other cats in the area?

Normally, I don't collar my cats - they are all indoor/outdoor rural
cats.  The only acceptable collars would be the breakaway or elastic
types, and those would likely need frequent replacement.  However, I
have three red tabby kittens I can't tell apart and I will have to
collar them with color coded collars.  Currently I have cheap elastic
bracelets on them, but those are too narrow to see easily and the
kittens are outgrowing them.  I bought a set of three wrist bands (for
$0.50) but they aren't much bigger.

Rather than mail-order expensive safety collars, I think I will try to
dye some elastic with markers or something and make my own in
quantity.

Urban cats should have identification - either a chip, a collar with
tag, or both so they can be returned if they escape from their
indoor-only homes.  That isn't much of an issue for rural
indoor/outdoor cats who have a cat flap for 24/7 in/out access.

Tags are neccessary for cats..especially if going outside at all and
maybe going off your proper...there is a various types of break aways
or escape collars...some are amde of elastic..some buckles that are
quick release so if found can be used again...my cats wear harnesses
and collars both ...collars priamrily for tags...remeber cats normally
seem to back up rather easily when somthing catches thier collars..then
theres the old fashion it actually breaks when caught..they don't seem
to last as long cause instead of the tree limb..thin one breaking with
the collar the collar stays put..etiher way cat is loose but...Peace of
Rainbeau fron Aladdin, Jingles, Dusty, and Kenda

Tags are neccessary for cats..especially if going outside at all and
maybe going off your proper...there is a various types of break aways
or escape collars...some are amde of elastic..some buckles that are
quick release so if found can be used again...my cats wear harnesses
and collars both ...collars priamrily for tags...remeber cats normally
seem to back up rather easily when somthing catches thier collars..then
theres the old fashion it actually breaks when caught..they don't seem
to last as long cause instead of the tree limb..thin one breaking with
the collar the collar stays put..etiher way cat is loose but...Peace of
Rainbeau fron Aladdin, Jingles, Dusty, and Kenda

A harness can serve the purpose of a collar and hold tags for ID
quite nicely, and is much much safer, if it gets caught on anything,
or the cat falls and it gets hooked on the way down, then
the harness holds the cat in a non-threatening position, rather
than the collar which could strangle the cat if it doesn't break
away.  My cats have all worn harnesses, which make even
vet visits quicker and less painful, as the cat becomes
much easier to manage without needing a human stranglehold
to keep it still.

A harness has two main straps, one round the neck and
one round the chest, and a connecting strap up top
across the spine.  It also had an attachment for a leash.

--tension

make sure the collars are not on too tight.  also make sure they have
elasticated sections that will stretch if put under strain.  you can also
get breakaway collars.

it is scary, my cat is always losing collars.  we have found a few in the
branches of trees.